Novel sulfonate salts and derivatives, photoacid generators, resist compositions, and patterning process

ABSTRACT

Sulfonate salts have the formula: 
     CF 3 —CH(OCOR)—CF 2 SO 3   − M +  wherein R is C 1 -C 20  alkyl or C 6 -C 14  aryl, and M +  is a lithium, sodium, potassium, ammonium or tetramethylammonium ion. Onium salts, oximesulfonates and sulfonyloxyimides and other compounds derived from these sulfonate salts are effective photoacid generators in chemically amplified resist compositions.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional application of co-pending applicationSer. No. 11/397,526 to which priority is claimed under 35 U.S.C. §120.Priority is also claimed under 35 U.S.C. §119 on Patent Application Nos.2005-109903 and 2005-316096 filed in Japan on Apr. 6, 2005 and Oct. 31,2005, respectively. The entire contents of all are hereby incorporatedby reference.

TECHNICAL FIELD

This invention relates to photoacid generators, resist compositionscomprising the same, and a patterning process using the same. Moreparticularly, it relates to novel sulfonate salts and derivativesthereof suitable for use as photoacid generators for resistcompositions.

BACKGROUND OF THE INVENTION

While a number of recent efforts are being made to achieve a finerpattern rule in the drive for higher integration and operating speeds inLSI devices, DUV and VUV lithography is thought to hold particularpromise as the next generation in microfabrication technology. Inparticular, photolithography using an ArF excimer laser as the lightsource is thought requisite to the micropatterning technique capable ofachieving a feature size of 0.13 μm or less.

In the photolithography using an ArF excimer laser (wavelength 193 nm)as the light source, a high sensitivity resist material capable ofachieving a high resolution at a small dose of exposure is needed toprevent the degradation of precise and expensive optical systemmaterials. Among several measures for providing high sensitivity resistmaterial, the most common is to select each component which is highlytransparent at the wavelength of 193 nm. For example, poly(meth)acrylicacid and derivatives thereof, norbornene-maleic anhydride alternatingcopolymers, polynorbornene and metathesis ring-opening polymers havebeen proposed as the base resin. This choice is effective to some extentin that the transparency of a resin alone is increased.

Studies have also been made on photoacid generators. In prior artchemically amplified resist compositions for lithography using KrFexcimer laser, photoacid generators capable of generating alkyl- oraryl-sulfonic acid are used. However, the use of these photoacidgenerators in chemically amplified resist compositions for ArFlithography results in an insufficient acid strength to scissor acidlabile groups on the resin, a failure of resolution or a lowsensitivity, and is not suited for the microfabrication ofmicroelectronic devices.

For the above reason, photoacid generators capable of generatingperfluoroalkylsulfonic acid having a high acid strength are generallyused in ArF chemically amplified resist compositions. These photoacidgenerators capable of generating perfluoroalkylsulfonic acid havealready been developed for use in the KrF resist compositions. Forinstance, JP-A 2000-122296 and U.S. Pat. No. 6,048,672 (or JP-A11-282168) describe photoacid generators capable of generatingperfluorohexanesulfonic acid, perfluorooctanesulfonic acid,perfluoro-4-ethylcyclohexanesulfonic acid, and perfluorobutanesulfonicacid. JP-A 2002-214774, US Patent Application 2003-0113659 A1 (JP-A2003-140332) and US Patent Application 2002-0197558 A1 describe novelphotoacid generators capable of generating perfluoroalkyl ether sulfonicacids.

On the other hand, perfluorooctanesulfonic acid and homologues thereof(collectively referred to as PFOS) are considered problematic withrespect to their stability (or non-degradability) due to C—F bonds, andbiological concentration and accumulation due to hydrophobic andlipophilic natures. The US EPA adopted Significant New Use Rule, listing13 PFOS-related chemical substances and further listing 75 chemicalsubstances although their use in the photoresist field is excluded. SeeFederal Register/Vol. 67, No. 47, page 11008/Monday, Mar. 11, 2002, andFederal Register/Vol. 67, No. 236, page 72854/Monday, Dec. 9, 2002.

Facing the PFOS-related problems, manufacturers made efforts to developpartially fluorinated alkyl sulfonic acids having a reduced degree offluorine substitution. For instance, JP-A 2004-531749 describes thedevelopment of α,α-difluoroalkylsulfonic acid salts fromα,α-difluoroalkene and a sulfur compound and discloses a resistcomposition comprising a photoacid generator which generates suchsulfonic acid upon irradiation, specificallydi(4-tert-butylphenyl)iodonium1,1-difluoro-1-sulfonate-2-(1-naphthyl)ethylene. JP-A 2004-2252describes the development of α,α,β,β-tetrafluoroalkylsulfonic acid saltsfrom α,α,β,β-tetrafluoro-α-iodoalkane and sulfur compound and disclosesa photoacid generator capable of generating such a sulfonic acid and aresist composition comprising the same. JP-A 2004-307387 discloses2-(bicyclo[2.2.1]hept-2-yl)-1,1-difluoroethylsulfonic acid salts and amethod of preparing the same.

The substances disclosed in these patents have a reduced degree offluorine substitution, but suffer from several problems. They areinsufficient from the standpoint of decomposition because they do nothave decomposable substituent groups such as ester structure. A certainlimit is imposed on the molecular design for changing the size ofalkylsulfonic acid. The starting materials containing fluorine areexpensive.

The ArF lithography started partial use from the fabrication of 130-nmnode devices and became the main lithography since 90-nm node devices.Although lithography using F₂ laser (157 nm) was initially thoughtpromising as the next lithography for 45-nm node devices, itsdevelopment was retarded by several problems including the quality ofCaF₂ single crystal used in projection lens, a need for hard pelliclethat requires design changes of the optical system, and low etchresistance of resists. A highlight was suddenly placed on ArF immersionlithography. See Journal of Photopolymer Science and Technology, Vol.17, No. 4, p 587 (2004).

The resolution of a projection lens through which a pattern image isprojected onto a wafer increases as its numerical aperture (NA)increases. In the immersion lithography, the intervention of a liquidhaving a higher refractive index than air between the projection lensand the wafer allows the projection lens to be designed to a NA of 1.0or higher, achieving a higher resolution. As the liquid, water having arefractive index of 1.4366 is used while alcohols such as ethyleneglycol and glycerin are under investigation.

Regrettably, the immersion lithography gives rise to the problem thatthe resist pattern after development can collapse or deform into a T-topprofile. Also, minute water droplets are left on the resist and waferafter the immersion exposure, which can often cause damages and defectsto the resist pattern profile. There exists a need for a patterningprocess which can form a satisfactory resist pattern after developmentaccording to the immersion lithography.

DISCLOSURE OF THE INVENTION

The photoacid generator (PAG) produces an acid which must satisfy manyrequirements including a sufficient acid strength to cleave acid labilegroups in a resist material, an adequate diffusion in the resistmaterial, low volatility, minimal dissolution in water, and gooddegradability in that it is decomposed away after the expiration of itsrole in lithography without imposing a load to the environment. No acidsproduced by prior art PAGs satisfy these requirements.

An object of the invention is to provide sulfonate salts and derivativesthereof which have solved the problems of prior art photoacidgenerators, and especially restrain dissolution in water during ArFimmersion exposure, and are effectively used in the immersionlithography and thus suitable as a photoacid generator in resistmaterial or a precursor thereof. Another object is to provide aphotoacid generator, a resist composition, and a patterning process.

The inventors have found that by starting with1,1,1,3,3,3-hexafluoro-2-propanol which is readily available in theindustry, and reacting substituted or unsubstituted1,1,1,3,3,3-hexafluoropropen-2-yl aliphatic carboxylic acid esters oraromatic carboxylic acid esters with sulfur compounds such as sodiumsulfite or sodium hydrogen sulfite, there are formed1,1,3,3,3-pentafluoro-2-acyloxypropane-1-sulfonate salts or1,1,3,3,3-pentafluoro-2-arylcarbonyloxypropane-1-sulfonate salts; thatonium salts, oximesulfonates and sulfonyloxyimides and other compoundsderived from these sulfonate salts are effective photoacid generators inchemically amplified resist compositions. The present invention ispredicated on this finding.

The present invention provides sulfonate salts, derivatives thereof,photoacid generators, resist compositions and a patterning process,defined below.

[1] A sulfonate salt having the general formula (1):

CF₃—CH(OCOR)—CF₂SO₃ ⁻M⁺  (1)

wherein R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup, and M⁺ is a lithium, sodium, potassium, ammonium ortetramethylammonium ion.[2] A photoacid generator for chemically amplified resist compositionswhich generates a sulfonic acid upon exposure to high-energy radiationselected from UV, deep-UV, electron beam, x-ray, excimer laser,gamma-ray and synchrotron radiation, said sulfonic acid having thegeneral formula (1a):

CF₃—CH(OCOR)—CF₂SO₃ ⁻H⁺  (1a)

wherein R is as defined above.[3] A sulfonium salt having the general formula (2):

R¹R²R³S⁺CF₃—CH(OCOR)—CF₂SO₃ ⁻  (2)

wherein R is as defined above, R¹, R² and R³ are each independentlyselected from the class consisting of substituted or unsubstituted,straight or branched C₁-C₁₀ alkyl, alkenyl and oxoalkyl groups, andsubstituted or unsubstituted C₆-C₁₈ aryl, aralkyl and aryloxoalkylgroups, or any two or more of R¹, R² and R³ may bond together to form aring with the sulfur atom.[4] A sulfonium salt having the general formula (2a):

R′—(O)_(n)-PhS⁺Ph₂CF₃—CH(OCOR)—CF₂SO₃ ⁻  (2a)

wherein R is as defined above, R′ is a substituted or unsubstituted,straight, branched or cyclic C₁-C₂₀ alkyl or alkenyl group or asubstituted or unsubstituted C₆-C₁₄ aryl group, Ph is phenyl, and n is 0or 1.[5] A iodonium salt having the general formula (2b):

R′(O)_(n)-PhI⁺Ph(O)_(n)—R′CF₃—CH(OCOR)—CF₂SO₃ ⁻  (2b)

wherein R, R′, Ph and n are as defined above.[6] A N-sulfonyloxyimide compound having the general formula (3a):

wherein R is as defined above, X and Y are each independently hydrogenor a substituted or unsubstituted C₁-C₆ alkyl group, or X and Y may bondtogether to form a saturated or unsaturated C₆-C₁₂ ring with the carbonatoms to which they are attached, and Z is a single bond, double bond,methylene group or oxygen atom.[7] An oxime sulfonate compound having the general formula (3b):

wherein R is as defined above; n is 0 or 1; when n is 0, p is asubstituted or unsubstituted C₁-C₂₀ alkyl group or a substituted orunsubstituted C₆-C₁₂ aryl group; when n is 1, p is a substituted orunsubstituted C₁-C₂₀ alkylene group or a substituted or unsubstitutedC₆-C₁₂ arylene group; EWG is a cyano, trifluoromethyl, perfluoroethyl,perfluoropropyl, 5H-perfluoropentyl, 6H-perfluorohexyl, nitro or methylgroup, and when n is 1, two EWG's may bond together to form a ring of 6carbon atoms with the carbon atoms to which they are attached.[8] A resist composition comprising a base resin, an acid generator, anda solvent, said acid generator comprising a photoacid generator whichgenerates a sulfonic acid having formula (1a) as set forth in [2].[9] The resist composition of [8], wherein said base resin is at leastone polymer selected from the group consisting of poly(meth)acrylic acidand derivatives thereof, alternating copolymers of a cycloolefinderivative and maleic anhydride, copolymers of ternary or morecomponents comprising a cycloolefin derivative, maleic anhydride, andpolyacrylic acid or derivatives thereof, cycloolefinderivative-α-trifluoromethyl acrylate copolymers, polynorbornene,ring-opening metathesis polymers, and hydrogenated ring-openingmetathesis polymers.[10] The resist composition of [8], wherein said base resin is apolymeric structure containing silicon atoms.[11] The resist composition of [8], wherein said base resin is apolymeric structure containing fluorine atoms.[12] A chemically amplified positive resist composition comprising abase resin as set forth in [9], [10] or [11], a photoacid generatorwhich generates a sulfonic acid having formula (1a) as set forth in [2],and a solvent, wherein said base resin is insoluble or substantiallyinsoluble in a liquid developer, and becomes soluble under the action ofthe acid.[13] The chemically amplified positive resist composition of [12],further comprising a basic compound.[14] The chemically amplified positive resist composition of [12] or[13], further comprising a dissolution inhibitor.[15] A process for forming a pattern comprising the steps of applyingthe resist composition of any one of [8] to [14] onto a substrate toform a coating; heat treating the coating and exposing it to high-energyradiation having a wavelength of up to 200 nm through a photomask; andoptionally heat treating and developing the exposed coating with adeveloper.[16] The process of [15], wherein the exposing step relies on immersionlithography comprising directing radiation from an ArF excimer laserhaving a wavelength of 193 nm through a projection lens, with a liquidsuch as water, glycerin or ethylene glycol intervening between thecoated substrate and the projection lens.

BENEFITS OF THE INVENTION

The sulfonic acids of the invention have a wide spectrum of moleculardesign because the inclusion of an ester moiety within the moleculeallows for easy incorporation of substituent groups including less bulkyacyl groups, bulky acyl groups, benzoyl groups, naphthoyl groups andanthranyl groups. The photoacid generators that generate these sulfonicacids perform well without raising problems during the devicefabrication process including coating, pre-baking, exposure,post-exposure baking, and developing steps. The dissolution of sulfonicacids in water during the ArF immersion lithography is minimized, andthe influence of water droplets left on the wafer is minimized, with fewdefects being found. In the disposal of resist-containing waste liquidafter the device fabrication, ester moieties are subject to alkalinehydrolysis so that the sulfonic acids are transformed into lessaccumulative compounds of lower molecular weight. In the disposal bycombustion, the sulfonic acids are more combustible because of a lowdegree of fluorine substitution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the ¹H-NMR/D₂O spectrum of Anion 1 inSynthesis Example 9.

FIG. 2 is a diagram showing the ¹⁹F-NMR/D₂O spectrum of Anion 1 inSynthesis Example 9.

FIG. 3 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG1 inSynthesis Example 11.

FIG. 4 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG1 inSynthesis Example 11.

FIG. 5 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG2 inSynthesis Example 12.

FIG. 6 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG2 inSynthesis Example 12.

FIG. 7 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG3 inSynthesis Example 13.

FIG. 8 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG3 inSynthesis Example 13.

FIG. 9 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG4 inSynthesis Example 14.

FIG. 10 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG4 inSynthesis Example 14.

FIG. 11 is a diagram showing the ¹H-NMR/D₂O spectrum of Anion 3 inSynthesis Example 27.

FIG. 12 is a diagram showing the ¹⁹F-NMR/D₂O spectrum of Anion 3 inSynthesis Example 27.

FIG. 13 is a diagram showing the ¹H-NMR/D₂O spectrum of Anion 4 inSynthesis Example 28.

FIG. 14 is a diagram showing the ¹⁹F-NMR/D₂O spectrum of Anion 4 inSynthesis Example 28.

FIG. 15 is a diagram showing the ¹H-NMR/D₂O spectrum of Anion 5 inSynthesis Example 29.

FIG. 16 is a diagram showing the ¹⁹F-NMR/D₂O spectrum of Anion 5 inSynthesis Example 29.

FIG. 17 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of Anion 6 inSynthesis Example 30.

FIG. 18 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of Anion 6 inSynthesis Example 30.

FIG. 19 is a diagram showing the ¹H-NMR/D₂O spectrum of Anion 7 inSynthesis Example 31.

FIG. 20 is a diagram showing the ¹⁹F-NMR/D₂O spectrum of Anion 7 inSynthesis Example 31.

FIG. 21 is a diagram showing the ¹H-NMR/CDCl₃ spectrum of PAG17 inSynthesis Example 33.

FIG. 22 is a diagram showing the ¹⁹F-NMR/CDCl₃ spectrum of PAG17 inSynthesis Example 33.

FIG. 23 is a diagram showing the ¹H-NMR/CDCl₃ spectrum of PAG18 inSynthesis Example 34.

FIG. 24 is a diagram showing the ¹⁹F-NMR/CDCl₃ spectrum of PAG18 inSynthesis Example 34.

FIG. 25 is a diagram showing the ¹H-NMR/CDCl₃ spectrum of PAG20 inSynthesis Example 36.

FIG. 26 is a diagram showing the ¹⁹F-NMR/CDCl₃ spectrum of PAG20 inSynthesis Example 36.

FIG. 27 is a diagram showing the ¹H-NMR/CDCl₃ spectrum of PAG22 inSynthesis Example 38.

FIG. 28 is a diagram showing the ¹⁹F-NMR/CDCl₃ spectrum of PAG22 inSynthesis Example 38.

FIG. 29 is a diagram showing the ¹H-NMR/CDCl₃ spectrum of PAG25 inSynthesis Example 41.

FIG. 30 is a diagram showing the ¹⁹F-NMR/CDCl₃ spectrum of PAG25 inSynthesis Example 41.

FIG. 31 is a diagram showing the ¹H-NMR/CDCl₃ spectrum of PAG26 inSynthesis Example 42.

FIG. 32 is a diagram showing the ¹⁹F-NMR/CDCl₃ spectrum of PAG26 inSynthesis Example 42.

FIG. 33 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG27 inSynthesis Example 43.

FIG. 34 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG27 inSynthesis Example 43.

FIG. 35 is a diagram showing the ¹H-NMR/DMSO-d₆ spectrum of PAG28 inSynthesis Example 44.

FIG. 36 is a diagram showing the ¹⁹F-NMR/DMSO-d₆ spectrum of PAG28 inSynthesis Example 44.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The notation (Cn—Cm) means a group containing from n to m carbon atomsper group.

Sulfonate Salt

The sulfonate salt of the invention has the general formula (1):

CF₃—CH(OCOR)—CF₂SO₃ ⁻M⁺  (1)

wherein R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup, and M⁺ is a lithium, sodium, potassium, ammonium ortetramethylammonium ion.

In formula (1), R is a substituted or unsubstituted, straight, branchedor cyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄aryl group. Examples of suitable alkyl and aryl groups include methyl,ethyl, n-propyl, sec-propyl, cyclopropyl, n-butyl, sec-butyl, iso-butyl,tert-butyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, n-octyl,n-decyl, n-dodecyl, 1-adamantyl, 2-adamantyl, bicyclo[2.2.1]hepten-2-yl,phenyl, 4-methoxyphenyl, 4-tert-butylphenyl, 4-biphenyl, 1-naphthyl,2-naphthyl, 10-anthranyl and 2-furanyl. M⁺ is a lithium ion, sodium ion,potassium ion, ammonium ion or tetramethylammonium ion.

For simplicity of synthesis and ease of isolation, only lithium, sodium,potassium, ammonium and tetramethylammonium salts are specified hereinas the sulfonate salt. Nevertheless, salts of divalent cations likecalcium and magnesium salts are acceptable. No particular limit isimposed on sulfonate salts as long as they can exist as stable salts.

Preferred among R groups are tert-butyl, cyclohexyl, 1-adamantyl,phenyl, 4-tert-butylphenyl, 4-methoxyphenyl, 4-biphenyl, 1-naphthyl and2-naphthyl. More preferred are tert-butyl, cyclohexyl, phenyl and4-tert-butylphenyl.

Photoacid Generator

The photoacid generators of the invention are compounds derived from thesulfonate salts having formula (1), typically sulfonium salts, iodoniumsalts, oximesulfonates and sulfonyloxyimides. These compounds aresensitive to high-energy radiation such as UV, deep-UV, electron beam,x-ray, excimer laser, gamma-ray and synchrotron radiation and generatesulfonic acids having the general formula (1a) so that they are usefulas photoacid generators in chemically amplified resist compositions.

CF₃—CH(OCOR)—CF₂SO₃ ⁻H⁺  (1a)

Herein R is a substituted or unsubstituted, straight, branched or cyclicC₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ aryl group.

Examples of R in formula (1a) are the same as described for formula (1).Illustrative examples of the sulfonic acid are given below.

Of the groups represented by R in formula (1a), tert-butyl, cyclohexyl,1-adamantyl, phenyl, 4-tert-butylphenyl, 4-biphenyl, 1-naphthyl and2-naphthyl are preferred.

Sulfonium Salt

The sulfonium salt of the invention has the general formula (2):

R¹R²R³S⁺CF₃—CH(OCOR)—CF₂SO₃ ⁻  (2)

wherein R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup, R¹, R² and R³ are each independently selected from amongsubstituted or unsubstituted, straight or branched C₁-C₁₀ alkyl, alkenyland oxoalkyl groups, and substituted or unsubstituted C₆-C₁₈ aryl,aralkyl and aryloxoalkyl groups, or any two or more of R¹, R² and R³ maybond together to form a ring with the sulfur atom.

In formula (2), examples of R are the same as described for formula (1).R¹, R² and R³ are each independently selected from among substituted orunsubstituted, straight or branched C₁-C₁₀ alkyl, alkenyl and oxoalkylgroups, and substituted or unsubstituted C₆-C₁₈ aryl, aralkyl andaryloxoalkyl groups, or any two or more of R¹, R² and R³ may bondtogether to form a ring with the sulfur atom. Suitable alkyl groupsinclude methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl,cycloheptyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl,norbornyl, and adamantyl. Suitable alkenyl groups include vinyl, allyl,propenyl, butenyl, hexenyl, and cyclohexenyl. Suitable oxoalkyl groupsinclude 2-oxocyclopentyl, 2-oxocyclohexyl, 2-oxopropyl, 2-oxoethyl,2-cyclopentyl-2-oxoethyl, 2-cyclohexyl-2-oxoethyl, and2-(4-methyl-cyclohexyl)-2-oxoethyl. Suitable aryl groups include phenyl,naphthyl, and thienyl; 4-hydroxyphenyl; alkoxyphenyl groups such asp-methoxyphenyl, m-methoxyphenyl, o-methoxyphenyl, p-ethoxyphenyl,p-tert-butoxyphenyl, and m-tert-butoxyphenyl; alkylphenyl groups such as2-methylphenyl, 3-methylphenyl, 4-methylphenyl, ethylphenyl,4-tert-butylphenyl, 4-butylphenyl, and 2,4-dimethylphenyl; alkylnaphthylgroups such as methylnaphthyl and ethylnaphthyl; alkoxynaphthyl groupssuch as methoxynaphthyl and ethoxynaphthyl; dialkylnaphthyl groups suchas dimethylnaphthyl and diethylnaphthyl; and dialkoxynaphthyl groupssuch as dimethoxynaphthyl and diethoxynaphthyl. Suitable aralkyl groupsinclude benzyl, 1-phenylethyl and 2-phenylethyl. Suitable aryloxoalkylgroups include 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl,2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl. When two ormore of R¹, R² and R³ bond together to form a ring structure with thesulfur atom, 1,4-butylene and 3-oxa-1,5-pentylene are exemplary of each.Also included are aryl groups having polymerizable substituent radicalssuch as acryloyloxy and methacryloyloxy radicals, examples of which are4-(acryloyloxy)phenyl, 4-(methacryloyloxy)phenyl, 4-vinyloxyphenyl, and4-vinylphenyl groups.

Illustrative examples of the sulfonium cation includetriphenylsulfonium, 4-hydroxyphenyldiphenylsulfonium,bis(4-hydroxyphenyl)phenylsulfonium, tris(4-hydroxyphenyl)sulfonium,(4-tert-butoxyphenyl)diphenylsulfonium,bis(4-tert-butoxyphenyl)phenylsulfonium,tris(4-tert-butoxyphenyl)sulfonium,(3-tert-butoxyphenyl)diphenylsulfonium,bis(3-tert-butoxyphenyl)phenylsulfonium,tris(3-tert-butoxyphenyl)sulfonium,(3,4-di-tert-butoxyphenyl)diphenylsulfonium,bis(3,4-di-tert-butoxyphenyl)phenylsulfonium,tris(3,4-di-tert-butoxyphenyl)sulfonium,diphenyl(4-thiophenoxyphenyl)sulfonium,(4-tert-butoxycarbonylmethyloxyphenyl)diphenylsulfonium,tris(4-tert-butoxycarbonylmethyloxyphenyl)sulfonium,(4-tert-butoxyphenyl)bis(4-dimethylaminophenyl)sulfonium,tris(4-dimethylaminophenyl)sulfonium, 2-naphthyldiphenylsulfonium,dimethyl-2-naphthylsulfonium, 4-hydroxyphenyldimethylsulfonium,4-methoxyphenyldimethylsulfonium, trimethylsulfonium,2-oxocyclohexylcyclohexylmethylsulfonium, trinaphthylsulfonium,tribenzylsulfonium, diphenylmethylsulfonium, dimethylphenylsulfonium,2-oxo-2-phenylethylthiacyclopentanium, diphenyl-2-thienylsulfonium,4-n-butoxynaphthyl-1-thiacyclopentanium,2-n-butoxynaphthyl-1-thiacyclopentanium,4-methoxynaphthyl-1-thiacyclopentanium, and2-methoxynaphthyl-1-thiacyclopentanium. Preferred cations aretriphenylsulfonium, 4-tert-butylphenyldiphenylsulfonium,4-tert-butoxyphenyldiphenylsulfonium, tris(4-tert-butylphenyl)sulfonium,and (4-tert-butoxycarbonylmethyloxyphenyl)diphenylsulfonium.

Also included are 4-(methacryloyloxy)phenyldiphenylsulfonium,4-(acryloyloxy)phenyldiphenylsulfonium,4-(methacryloyloxy)phenyldimethylsulfonium,4-(acryloyloxy)phenyldimethylsulfonium, and the like. For thesepolymerizable sulfonium cations, reference may be made to JP-A 4-230645and JP-A 2005-84365. These polymerizable sulfonium salts may be used asa monomer in forming a polymer to be described later.

In one embodiment, the sulfonium salt has the general formula (2a):

R′(O)_(n)-PhS⁺Ph₂CF₃—CH(OCOR)—CF₂SO₃ ⁻  (2a)

wherein R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup, R′ is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl or alkenyl group or a substituted or unsubstitutedC₆-C₁₄ aryl group, Ph is phenyl, and n is 0 or 1.

In formula (2a), examples of R are the same as described for formula(1). The subscript n is 0 or 1. The substitution position of R′—(O)_(n)—group is not particularly limited, but is preferably 4- or 3-position onthe phenyl group, and more preferably 4-position. Examples of groupsrepresented by R′ include methyl, ethyl, n-propyl, sec-propyl,cyclopropyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, n-pentyl,cyclopentyl, n-hexyl, cyclohexyl, n-octyl, n-decyl, n-dodecyl,1-adamantyl, 2-adamantyl, bicyclo[2.2.1]hepten-2-yl, phenyl,4-methoxyphenyl, 4-tert-butylphenyl, 4-biphenyl, 1-naphthyl, 2-naphthyl,10-anthranyl, and 2-furanyl. In the case of n=1, acryloyl, methacryloyl,vinyl, and allyl are exemplary of R′.

Illustrative examples of the sulfonium cation include4-methylphenyldiphenylsulfonium, 4-ethylphenyldiphenylsulfonium,4-tert-butylphenyldiphenylsulfonium,4-cyclohexylphenyldiphenylsulfonium, 4-n-hexylphenyldiphenylsulfonium,4-n-octylphenyldiphenylsulfonium, 4-methoxyphenyldiphenylsulfonium,4-ethoxyphenyldiphenylsulfonium, 4-tert-butoxyphenyldiphenylsulfonium,4-cyclohexyloxyphenyldiphenylsulfonium,4-n-hexyloxyphenyldiphenylsulfonium,4-n-octyloxyphenyldiphenylsulfonium,4-dodecyloxyphenyldiphenylsulfonium,4-trifluoromethylphenyldiphenylsulfonium,4-trifluoromethyloxyphenyldiphenylsulfonium,4-tert-butoxycarbonylmethyloxyphenyldiphenylsulfonium,4-(methacryloyloxy)phenyldiphenylsulfonium,4-(acryloyloxy)phenyldiphenylsulfonium,4-(methacryloyloxy)phenyldimethylsulfonium, and4-(acryloyloxy)phenyldimethylsulfonium.

Iodonium Salt

A further embodiment of the invention is a iodonium salt having thegeneral formula (2b):

R′(O)_(n)-PhI⁺Ph(O)_(n)—R′CF₃—CH(OCOR)—CF₂SO₃ ⁻  (2b)

wherein R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup, R′ is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl or alkenyl group or a substituted or unsubstitutedC₆-C₁₄ aryl group, Ph is phenyl, and n is 0 or 1.

R, R′, n and Ph in formula (2b) are as defined above. The substitutionposition of R′—(O)_(n)— group is not particularly limited, but ispreferably 4- or 3-position on the phenyl group, and more preferably4-position.

Illustrative examples of the iodonium cation includebis(4-methylphenyl)iodonium, bis(4-ethylphenyl)iodonium,bis(4-tert-butylphenyl)iodonium,bis(4-(1,1-dimethylpropyl)phenyl)iodonium,4-methoxyphenylphenyliodonium, 4-tert-butoxyphenylphenyliodonium,4-acryloyloxyphenylphenyliodonium, and4-methacryloyloxyphenylphenyliodonium, with thebis(4-tert-butylphenyl)iodonium being preferred.

N-sulfonyloxyimide

A further embodiment of the invention is a N-sulfonyloxyimide compoundhaving the general formula (3a):

wherein R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup; X and Y are each independently hydrogen or a substituted orunsubstituted C₁-C₆ alkyl group, or X and Y may bond together to form asaturated or unsaturated C₆-C₁₂ ring with the carbon atoms to which theyare attached; and Z is a single bond, double bond, methylene group oroxygen atom.

Illustrative examples of the imide skeleton excluding the sulfonatemoiety are given below. For the imide skeleton, reference may be made toJP-A 2003-252855.

Oxime Sulfonate

A further embodiment of the invention is an oxime sulfonate compoundhaving the general formula (3b):

wherein R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup, and n is 0 or 1; when n is 0, p is a substituted or unsubstitutedC₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₂ aryl group;when n is 1, p is a substituted or unsubstituted C₁-C₂₀ alkylene groupor a substituted or unsubstituted C₆-C₁₂ arylene group; and EWG is acyano, trifluoromethyl, perfluoroethyl, perfluoropropyl,5H-perfluoropentyl, 6H-perfluorohexyl, nitro or methyl group, and when nis 1, two EWG's may bond together to form a ring of 6 carbon atoms withthe carbon atoms to which they are attached.

The skeletons of these oxime sulfonates are described in U.S. Pat. No.6,261,738, JP-A 9-95479, JP-A 9-208554, JP-A 9-230588, Japanese PatentNo. 2,906,999, JP-A 9-301948, JP-A 2000-314956, JP-A 2001-233842, andInternational Publication 2004-074242.

Exemplary skeletons of oxime sulfonates excluding the sulfonate moietyare given below.

Described below is how to synthesize the sulfonate salt having formula(1).

Synthesis may be carried out by reacting1,1,3,3,3-pentafluoropropen-2-yl aliphatic carboxylate or aromaticcarboxylate, typically 1,1,3,3,3-pentafluoropropen-2-yl benzoate whichwas developed by Nakai et al. using 1,1,1,3,3,3-hexafluoro-2-propanol asthe starting reactant (see Tetrahedron Lett., Vol. 29, 4119 (1988)),with sodium hydrogen sulfite or sodium sulfite in the presence of aradical initiator such as azobisisobutyronitrile or benzoyl peroxide ina solvent which is water or alcohol or a mixture thereof. See R. B.Wagner et al., Synthetic Organic Chemistry, pp. 813-814, John Wiley &Sons, Inc. (1965). More specifically, the carboxylic acid ester moietyof a sulfonate salt having formula (1) obtained by the above method or asulfonate salt having formula (2), (2a), (2b), (3a) or (3b) is subjectedto hydrolysis using alkali such as sodium hydroxide or potassiumhydroxide or solvolysis using alcohol and base, and then reacted withany appropriate one of aliphatic carboxylic halides, aliphaticcarboxylic anhydrides, aromatic carboxylic halides, and aromaticcarboxylic anhydrides, whereby a sulfonate salt having formula (1) or aphotoacid generator having formula (2), (2a), (2b), (3a) or (3b) havinga different carboxylic acid ester structure from the original carboxylicacid ester structure.

In preparing the sulfonate salt described above, a sulfonate salt of thefollowing general formula (1′) or (1″) corresponding to the sulfonatesalt of formula (1) with hydrogen fluoride being eliminated cansometimes form as well.

CF₃—C(OCOR)═CFSO₃ ⁻M⁺  (1′)

CF₂═C(OCOR)CF₂SO₃ ^(−M) ⁺  (1″)

Herein, R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup, and M⁺ is a lithium, sodium, potassium, ammonium ortetramethylammonium ion.

When the sulfonate salt preparing method yields a mixture of suchsulfonate salts, the molar ratio of the sulfonate salt of formula (1) tothe sulfonate salt of formula (1′) or (1″) is often in a range from100:0 to 100:10, although the exact ratio varies with the type ofsubstituent group R and reaction conditions.

The sulfonate salt of formula (1′) or (1″) may be used alone or inadmixture with the sulfonate salt of formula (1) to synthesize aphotoacid generator, sulfonium salt, iodonium salt, N-sulfonyloxyimidecompound or oxime sulfonate compound. The photoacid generatorsynthesized using the sulfonate salt of formula (1′) or (1″) may beincluded in resist compositions, especially chemically amplifiedpositive resist compositions, or applied to a patterning process.

Specifically, still further embodiments of the invention include

a photoacid generator for chemically amplified resist compositions whichgenerates a sulfonic acid having the general formula (1′a) or (1″a) uponexposure to high-energy radiation selected from UV, deep-UV, electronbeam, x-ray, excimer laser, gamma-ray and synchrotron radiation,

CF₃—C(OCOR)═CFSO₃ ⁻H⁺  (1a)

CF₂═C(OCOR)CF₂SO₃ ⁻H⁺  (1″a)

wherein R is as defined above;

a sulfonium salt having the general formula (2′) or (2″):

R¹R²R³S⁺CF₃—C(OCOR)═CFSO₃ ⁻  (2′)

R¹R²R³S⁺CF₂═C(OCOR)CF₂SO₃ ⁻  (2)

wherein R is as defined above, R¹, R² and R³ are each independentlyselected from among substituted or unsubstituted, straight or branchedC₁-C₁₀ alkyl, alkenyl and oxoalkyl groups, and substituted orunsubstituted C₆-C₁₈ aryl, aralkyl and aryloxoalkyl groups, or any twoor more of R¹, R² and R³ may bond together to form a ring with thesulfur atom;

a sulfonium salt having the general formula (2′a) or (2″a):

R′—(O)_(n)-PhS+Ph₂CF₃—C(OCOR)═CFSO₃ ⁻  (2′a)

R′—(O)_(n)-PhS⁺Ph₂CF₂═C(OCOR)CF₂SO₃ ⁻  (2″a)

wherein R is as defined above, R′ is a substituted or unsubstituted,straight, branched or cyclic C₁-C₂₀ alkyl or alkenyl group or asubstituted or unsubstituted C₆-C₁₄ aryl group, Ph is phenyl, and n is 0or 1;

a iodonium salt having the general formula (2′b) or (2″b):

R′(O)_(n)-PhI⁺Ph(O)_(n)—R′CF₃—C(OCOR)═CFSO₃ ⁻  (2′b)

R′(O)_(n)-PhI⁺Ph(O)_(n)—R′CF₂═C(OCOR)CF₂SO₃ ⁻  (2″b)

wherein R, R′, Ph and n are as defined above;

a N-sulfonyloxyimide compound having the general formula (3′a) or (3″a):

wherein R is as defined above, X and Y are each independently hydrogenor a substituted or unsubstituted C₁-C₆ alkyl group, or X and Y may bondtogether to form a saturated or unsaturated C₆-C₁₂ ring with the carbonatoms to which they are attached, and Z is a single bond, double bond,methylene group or oxygen atom; and

an oxime sulfonate compound having the general formula (3′b) or (3″b):

wherein R is as defined above, n is 0 or 1, when n is 0, p is asubstituted or unsubstituted C₁-C₂₀ alkyl group or a substituted orunsubstituted C₆-C₁₂ aryl group, when n is 1, p is a substituted orunsubstituted C₁-C₂₀ alkylene group or a substituted or unsubstitutedC₆-C₁₂ arylene group, EWG is a cyano, trifluoromethyl, perfluoroethyl,perfluoropropyl, 5H-perfluoropentyl, 6H-perfluorohexyl, nitro or methylgroup, and when n is 1, two EWG's may bond together to form a ring of 6carbon atoms with the carbon atoms to which they are attached.

The compounds of the still further embodiments serve as photoacidgenerators and may be included in resist compositions or applied topatterning processes in the same manner as the preceding embodiments ofthe invention.

It is understood that the sulfonate salts of formula (1′) or (1″) orhomologues can be identified by analyzing a mixture thereof with asulfonate salt of formula (1) by ¹⁹F-NMR spectroscopy as will bedemonstrated in Synthesis Examples later. From the minute peaks ofdoublet near −66 ppm and quartet near −125 ppm which are observed inaddition to the peaks of the major component, the presence of (1′) typesulfonate anion is presumed. These chemical shifts are inherent to theexample of PAG2 in FIG. 6 while chemical shifts differ with a particularcompound, measuring solvent and measuring conditions. On time-of-flightmass spectrometry, aside from the major anion, an anion having a massnumber smaller by 20 than the major anion is sometimes observed on thenegative side as a minute peak although a chance of observation dependson an existence ratio and sensitivity.

In converting the sulfonate salts of formula (1) to the sulfonium andiodonium salts of formulae (2), (2a) and (2b), the reaction may beperformed by a conventional anion exchange method. The sulfonium andiodonium salts can be synthesized in accordance with the teachings ofThe Chemistry of Sulfonium Group Part 1, 267-312, John-Wiley & Sons(1981), Advances in Photochemistry, Vol. 17, 313-320, John-Wiley & Sons(1992), J. Org. Chem., 53, 5571-5573, 1988, JP-A 8-311018, JP-A 9-15848,JP-A 2001-122850, JP-A 7-25846, JP-A 2001-181221, JP-A 2002-193887, andJP-A 2002-193925.

The onium cation having an acryloyloxy or methacryloyloxy group as thepolymerizable substituent group can be synthesized by reacting(currently available) hydroxyphenyldiphenylsulfonium halide withacryloyl chloride or methacryloyl chloride under basic conditionsaccording to the methods described in JP-A 4-230645 and JP-A 2005-84365.

Anion exchange may be performed in an alcohol solvent such as methanolor ethanol or a two-layer system of dichloromethane and water or thelike. Alternatively, anion exchange may be performed by another recipeof reacting a corresponding methyl sulfonate with sulfonyl halide oriodonium halide, and removing the halide ion as methyl halide, asdescribed in JP-A 2002-167340.

Also, the compounds of formula (3a) and (3b) can be synthesized byreacting the sulfonate salt with a chlorinating agent such as thionylchloride, phosphorus oxychloride or phosphorus pentachloride to form acorresponding sulfonyl chloride or sulfonic acid anhydride, and furtherreacting with N-hydroxydicarboxylimide or oximes in a conventional way.For the synthesis of imide sulfonate or oxime sulfonate, referenceshould be made to the above-cited JP-A 2003-252855, U.S. Pat. No.6,261,738, JP-A 9-95479, JP-A 9-208554, JP-A 9-230588, Japanese PatentNo. 2,906,999, JP-A 9-301948, JP-A 2000-314956, JP-A 2001-233842, andInternational Publication 2004-074242.

As described above, a first embodiment of the present invention providesa sulfonate salt having formula (1). A second embodiment of the presentinvention provides a photoacid generator for chemically amplified resistcompositions which generates a sulfonic acid having formula (Ia) uponexposure to high-energy radiation. A third embodiment of the presentinvention provides a sulfonium salt, iodonium salt, dicarboxylimidesulfonate, and oxime sulfonate serving as photoacid generators inchemically amplified resist compositions. A fourth embodiment of thepresent invention provides a resist composition comprising a photoacidgenerator which generates a sulfonic acid having formula (Ia) uponexposure to high-energy radiation and a resin which changes itssolubility in an alkaline developer liquid under the action of acid.

The resist composition of the invention is typically embodied as

(i) a chemically amplified positive resist composition comprising

(A) a photoacid generator which generates a sulfonic acid having formula(Ia) upon exposure to high-energy radiation,

(B) an organic solvent,

(C) a base resin which changes its solubility in an alkaline developerliquid under the action of acid, and

one or more optional components including (D) a basic compound, (E) aphotoacid generator other than (A), (F) an organic acid derivativeand/or fluorinated alcohol, and (G) a dissolution inhibitor having amolecular weight of up to 3,000; and

(ii) a chemically amplified negative resist composition comprising

(A) a photoacid generator which generates a sulfonic acid having formula(Ia) upon exposure to high-energy radiation,

(B) an organic solvent,

(C′) a base resin which is normally alkali soluble, but becomessubstantially alkali insoluble under the action of a crosslinker,

(H) a crosslinker which induces crosslinkage under the action of acid,and

one or more optional components including (D) a basic compound and (E) aphotoacid generator other than (A).

The PAG which generates a sulfonic acid having formula (1a) as component(A) is as described above. More specifically, it is a compound havingformula (2), (2a), (2b), (3a) or (3b). In the resist composition, thePAG is compounded in an amount of 0.1 to 10 parts, more preferably 1 to5 parts by weight per 100 parts by weight of the base resin.

Component B

The organic solvent used herein may be any organic solvent in which thebase resin, photoacid generator, and other components are soluble.Illustrative, non-limiting, examples of the organic solvent includeketones such as cyclohexanone and methyl amyl ketone; alcohols such as3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether,ethylene glycol monomethyl ether, propylene glycol monoethyl ether,ethylene glycol monoethyl ether, propylene glycol dimethyl ether, anddiethylene glycol dimethyl ether; esters such as propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether acetate,ethyl lactate, ethyl pyruvate, butyl acetate, methyl3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate,tert-butyl propionate, and propylene glycol mono-tert-butyl etheracetate; and lactones such as γ-butyrolactone. These solvents may beused alone or in combinations of two or more thereof. Of the aboveorganic solvents, it is recommended to use diethylene glycol dimethylether, 1-ethoxy-2-propanol, propylene glycol monomethyl ether acetate(PGMEA), cyclohexanone and mixtures thereof because the photoacidgenerator is most soluble therein.

An appropriate amount of the organic solvent used is about 200 to 3,000parts, especially about 400 to 2,000 parts by weight per 100 parts byweight of the base resin.

Component C

The base resins used as component (C) or (C′) in the inventivecompositions include polyhydroxystyrene (PHS), and copolymers of PHSwith styrene, (meth)acrylic acid esters or other polymerizable olefiniccompounds, for KrF excimer laser resist use; (meth)acrylic acid esterpolymers, alternating copolymers of cycloolefin with maleic anhydride,copolymers further containing vinyl ethers or (meth)acrylic acid esters,polynorbornene, ring-opening metathesis polymerized cycloolefins, andhydrogenated ring-opening metathesis polymerized cycloolefins, for ArFexcimer laser resist use; and fluorinated forms of the foregoingpolymers (for both KrF and ArF laser uses) for F₂ excimer laser resistuse, although the base resins are not limited to these polymers.

Understandably, the sulfonium salts and iodonium salts havingpolymerizable substituent groups according to the invention may be usedas a monomer component in forming the base resin. Typical sulfonium andiodonium salts for such use are combinations of onium cations such as4-(acryloyloxy)phenyldiphenylsulfonium,4-(methacryloyloxy)phenyldiphenylsulfonium,4-(acryloyloxy)phenylphenyliodonium, and4-(methacryloyloxy)phenylphenyliodonium cations with anions such as1,1,3,3,3-pentafluoro-2-benzoyloxypropane-1-sulfonate,1,1,3,3,3-pentafluoro-2-pivaloyloxypropane-1-sulfonate, and1,1,3,3,3-pentafluoro-2-cyclohexanecarbonyloxypropane-1-sulfonateanions.

The base resins may be used alone or in admixture of two or more. In thecase of positive resist compositions, it is a common practice tosubstitute acid labile groups for hydroxyl groups on phenol, carboxylgroups or fluorinated alkyl alcohols for reducing the rate ofdissolution in unexposed regions.

The base resins are not limited to the foregoing resins. Use may also bemade of the resins described in the following patents.

JP-A 2000-159758 JP-A 2000-186118 JP-A 2000-309611 JP-A 2000-327633 JP-A2000-330283 JP-A 2001-329052 JP-A 2002-202609 JP-A 2002-161116 JP-A2003-2883 JP-A 2003-20313 JP-A 2003-26728 JP-A 2003-34706 JP-A2003-64134 JP-A 2003-66612 JP-A 2003-113213 JP-A 2003-316027 JP-A2003-321466 JP-A 2004-143153 JP-A 2004-124082 JP-A 2004-115486 JP-A2004-62175

In a preferred embodiment, the base resin is at least one polymerselected from among poly(meth)acrylic acid and derivatives thereof,alternating copolymers of a cycloolefin derivative and maleic anhydride,copolymers of three or more components comprising a cycloolefinderivative, maleic anhydride, and polyacrylic acid or derivativesthereof, cycloolefin derivative-α-trifluoromethyl acrylate copolymers,polynorbornene, ring-opening metathesis polymers, and hydrogenatedring-opening metathesis polymers.

In another preferred embodiment, the base resin is a polymeric structurecontaining silicon atoms or a polymeric structure containing fluorineatoms. Such polymers include those described in the following patents.

JP-A 2005-8765 JP-A 2004-354417 JP-A 2004-352743 JP-A 2004-331854 JP-A2004-331853 JP-A 2004-292781 JP-A 2004-252405 JP-A 2004-190036 JP-A2004-115762 JP-A 2004-83873 JP-A 2004-59844 JP-A 2004-35671 JP-A2004-83900 JP-A 2004-99689 JP-A 2004-145048 JP-A 2004-217533 JP-A2004-231815 JP-A 2004-244439 JP-A 2004-256562 JP-A 2004-307447 JP-A2004-323422 JP-A 2005-29527 JP-A 2005-29539

Included in the chemically amplified positive resist composition is abase resin having acid labile groups which is normally insoluble orsubstantially insoluble in developer, but becomes soluble in developeras a result of the acid labile groups being eliminated under the actionof acid.

The acid labile groups to be introduced into the base resin may beselected from a variety of such groups, preferably from C₂-C₃₀ acetalgroups and tertiary C₄-C₃₀ alkyl groups having the formulae (C1) and(C2), respectively.

In formulae (C1) and (C2), R⁴ and R⁵ each are hydrogen or a straight,branched or cyclic C₁-C₂₀ alkyl group, which may contain a hetero atomsuch as oxygen, sulfur, nitrogen or fluorine, R⁶, R⁷, R⁸ and R⁹ each area straight, branched or cyclic C₁-C₂₀ alkyl group, a C₆-C₁₀ aryl groupor a C₇-C₁₀ aralkyl group, which may contain a hetero atom such asoxygen, sulfur, nitrogen or fluorine. A pair of R⁴ and R⁵, a pair of R⁴and R⁶, a pair of R⁵ and R⁶, a pair of R⁷ and R⁸, a pair of R⁷ and R⁹,or a pair of R⁸ and R⁹, taken together, may form a ring of 3 to 30carbon atoms with the carbon atom to which they are attached.

Illustrative examples of the acetal group of formula (C1) include, butare not limited to, methoxymethyl, ethoxymethyl, propoxymethyl,butoxymethyl, isopropoxymethyl, t-butoxymethyl, 1-methoxyethyl,1-methoxypropyl, 1-methoxybutyl, 1-ethoxyethyl, 1-ethoxypropyl,1-ethoxybutyl, 1-propoxyethyl, 1-propoxypropyl, 1-propoxybutyl,1-cyclopentyloxyethyl, 1-cyclohexyloxyethyl, 2-methoxyisopropyl,2-ethoxyisopropyl, 1-phenoxyethyl, 1-benzyloxyethyl, 1-phenoxypropyl,1-benzyloxypropyl, 1-adamantyloxyethyl, 1-adamantyloxypropyl,2-tetrahydrofuryl, 2-tetrahydro-2H-pyranyl,1-(2-cyclohexanecarbonyloxyethoxy)ethyl,1-(2-cyclohexanecarbonyloxyethoxy)propyl,1-[2-(1-adamantylcarbonyloxy)ethoxy]ethyl, and1-[2-(1-adamantylcarbonyloxy)ethoxy]propyl.

Illustrative examples of the tertiary alkyl group of formula (C2)include, but are not limited to, t-butyl, t-pentyl,1-ethyl-1-methylpropyl, 1,1-diethylpropyl, 1,1,2-trimethylpropyl,1-adamantyl-1-methylethyl, 1-methyl-1-(2-norbornyl)ethyl,1-methyl-1-(tetrahydrofuran-2-yl)ethyl,1-methyl-1-(7-oxanorbornan-2-yl)ethyl, 1-methylcyclopentyl,1-ethylcyclopentyl, 1-propylcyclopentyl, 1-cyclopentylcyclopentyl,1-cyclohexylcyclopentyl, 1-(2-tetrahydrofuryl)cyclopentyl,1-(7-oxanorbornan-2-yl)cyclopentyl, 1-methylcyclohexyl,1-ethylcyclohexyl, 1-cyclopentylcyclohexyl, 1-cyclohexylcyclohexyl,2-methyl-2-norbornyl, 2-ethyl-2-norbornyl,8-methyl-8-tricyclo[5.2.1.0^(2,6)]decyl,8-ethyl-8-tricyclo[5.2.1.0^(2,6)]decyl,3-methyl-3-tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecyl,3-ethyl-3-tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecyl,2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 1-methyl-3-oxo-1-cyclohexyl,1-methyl-1-(tetrahydrofuran-2-yl)ethyl, 5-hydroxy-2-methyl-2-adamantyl,and 5-hydroxy-2-ethyl-2-adamantyl.

In the base resin, at least 1 mol % of hydrogen atoms of hydroxyl groupsmay be substituted by acid labile groups of the following generalformula (C3a) or (C3b) for crosslinkage between molecules or within amolecule.

Herein, R¹⁰ and R¹¹ each are hydrogen or a straight, branched or cyclicalkyl group of 1 to 8 carbon atoms, or R¹⁰ and R¹¹, taken together, mayform a ring, with the proviso that each of R¹⁰ and R¹¹ is a straight orbranched alkylene group of 1 to 8 carbon atoms when they form a ring.R¹² is a straight, branched or cyclic alkylene group of 1 to 10 carbonatoms. Letter “a” is an integer of 1 to 7 and “b” is 0 or an integer of1 to 10. “A” is a (a+1)-valent aliphatic or alicyclic saturatedhydrocarbon group, aromatic hydrocarbon group or heterocyclic group of 1to 50 carbon atoms, which may have an intervening hetero atom and inwhich the hydrogen atom attached to a carbon atom may be partiallyreplaced by a hydroxyl group, carboxyl group, carbonyl group or fluorineatom. B is —CO—O—, —NHCO—O— or —NHCONH—.

Illustrative examples of the crosslinking acetal linkages represented byformulae (C3a) and (C3b) are given below as (C3)-1 through (C3)-8, butnot limited thereto.

Preferably the base resin has a weight average molecular weight (Mw) of2,000 to 100,000, as measured by gel permeation chromatography (GPC)versus polystyrene standards. With Mw below 2,000, film formation andresolution may become poor. With Mw beyond 100,000, resolution maybecome poor or foreign matter may generate during pattern formation.

In the base resin, the proportion of acid labile group-containingmonomer units relative to the other monomer units (constituent units) istypically in a range of 10 to 70%, preferably 20 to 60%, in caseintended for ArF excimer laser resist compositions; and typically in arange of 10 to 50%, preferably 20 to 40%, in case intended for KrFexcimer laser resist compositions.

The monomer units other than the acid labile group-containing monomerunits are preferably monomer units containing polar groups such asalcohols, fluorinated alcohols, and ether, lactone, ester, acidanhydride, and carboxylic acid in the case of the base resins for ArFexcimer laser resist compositions. The base resins for KrF excimer laserresist compositions may comprise units of styrene, indene and4-acetoxystyrene in addition to 4-hydroxystyrene units having no acidlabile groups incorporated. These monomer units may be of one type or oftwo or more different types.

Component D

The basic compound used as component (D) is preferably a compoundcapable of suppressing the rate of diffusion when the acid generated bythe photoacid generator diffuses within the resist film. The inclusionof this type of basic compound holds down the rate of acid diffusionwithin the resist film, resulting in better resolution. In addition, itsuppresses changes in sensitivity following exposure and reducessubstrate and environment dependence, as well as improving the exposurelatitude and the pattern profile.

Examples of basic compounds include primary, secondary, and tertiaryaliphatic amines, mixed amines, aromatic amines, heterocyclic amines,nitrogen-containing compounds with carboxyl group, nitrogen-containingcompounds with sulfonyl group, nitrogen-containing compounds withhydroxyl group, nitrogen-containing compounds with hydroxyphenyl group,alcoholic nitrogen-containing compounds, amide derivatives, and imidederivatives.

Examples of suitable primary aliphatic amines include ammonia,methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine,isobutylamine, sec-butylamine, tert-butylamine, pentylamine,tert-amylamine, cyclopentylamine, hexylamine, cyclohexylamine,heptylamine, octylamine, nonylamine, decylamine, dodecylamine,cetylamine, methylenediamine, ethylenediamine, andtetraethylenepentamine. Examples of suitable secondary aliphatic aminesinclude dimethylamine, diethylamine, di-n-propylamine, diisopropylamine,di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine,dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine,dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine,N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, andN,N-dimethyltetraethylenepentamine. Examples of suitable tertiaryaliphatic amines include trimethylamine, triethylamine,tri-n-propylamine, triisopropylamine, tri-n-butylamine,triisobutylamine, tri-sec-butylamine, tripentylamine,tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine,trioctylamine, trinonylamine, tridecylamine, tridodecylamine,tricetylamine, N,N,N′,N′-tetramethylmethylenediamine,N,N,N′,N′-tetramethylethylenediamine, andN,N,N′,N′-tetramethyltetraethylenepentamine.

Examples of suitable mixed amines include dimethylethylamine,methylethylpropylamine, benzylamine, phenethylamine, andbenzyldimethylamine. Examples of suitable aromatic and heterocyclicamines include aniline derivatives (e.g., aniline, N-methylaniline,N-ethylaniline, N-propylaniline, N,N-dimethylaniline, 2-methylaniline,3-methylaniline, 4-methylaniline, ethylaniline, propylaniline,trimethylaniline, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline,2,4-dinitroaniline, 2,6-dinitroaniline, 3,5-dinitroaniline, andN,N-dimethyltoluidine), diphenyl(p-tolyl)amine, methyldiphenylamine,triphenylamine, phenylenediamine, naphthylamine, diaminonaphthalene,pyrrole derivatives (e.g., pyrrole, 2H-pyrrole, 1-methylpyrrole,2,4-dimethylpyrrole, 2,5-dimethylpyrrole, and N-methylpyrrole), oxazolederivatives (e.g., oxazole and isooxazole), thiazole derivatives (e.g.,thiazole and isothiazole), imidazole derivatives (e.g., imidazole,4-methylimidazole, and 4-methyl-2-phenylimidazole), pyrazolederivatives, furazan derivatives, pyrroline derivatives (e.g., pyrrolineand 2-methyl-1-pyrroline), pyrrolidine derivatives (e.g., pyrrolidine,N-methylpyrrolidine, pyrrolidinone, and N-methylpyrrolidone),imidazoline derivatives, imidazolidine derivatives, pyridine derivatives(e.g., pyridine, methylpyridine, ethylpyridine, propylpyridine,butylpyridine, 4-(1-butylpentyl)pyridine, dimethylpyridine,trimethylpyridine, triethylpyridine, phenylpyridine,3-methyl-2-phenylpyridine, 4-tert-butylpyridine, diphenylpyridine,benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine,1-methyl-2-pyridine, 4-pyrrolidinopyridine, 1-methyl-4-phenylpyridine,2-(1-ethylpropyl)pyridine, aminopyridine, and dimethylaminopyridine),pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives,pyrazoline derivatives, pyrazolidine derivatives, piperidinederivatives, piperazine derivatives, morpholine derivatives, indolederivatives, isoindole derivatives, 1H-indazole derivatives, indolinederivatives, quinoline derivatives (e.g., quinoline and3-quinolinecarbonitrile), isoquinoline derivatives, cinnolinederivatives, quinazoline derivatives, quinoxaline derivatives,phthalazine derivatives, purine derivatives, pteridine derivatives,carbazole derivatives, phenanthridine derivatives, acridine derivatives,phenazine derivatives, 1,10-phenanthroline derivatives, adeninederivatives, adenosine derivatives, guanine derivatives, guanosinederivatives, uracil derivatives, and uridine derivatives.

Examples of suitable nitrogen-containing compounds with carboxyl groupinclude aminobenzoic acid, indolecarboxylic acid, and amino acidderivatives (e.g. nicotinic acid, alanine, alginine, aspartic acid,glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine,methionine, phenylalanine, threonine, lysine,3-aminopyrazine-2-carboxylic acid, and methoxyalanine). Examples ofsuitable nitrogen-containing compounds with sulfonyl group include3-pyridinesulfonic acid and pyridinium p-toluenesulfonate. Examples ofsuitable nitrogen-containing compounds with hydroxyl group,nitrogen-containing compounds with hydroxyphenyl group, and alcoholicnitrogen-containing compounds include 2-hydroxypyridine, aminocresol,2,4-quinolinediol, 3-indolemethanol hydrate, monoethanolamine,diethanolamine, triethanolamine, N-ethyldiethanolamine,N,N-diethylethanolamine, triisopropanolamine, 2,2′-iminodiethanol,2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol,4-(2-hydroxyethyl)morpholine, 2-(2-hydroxyethyl)pyridine,1-(2-hydroxyethyl)piperazine, 1-[2-(2-hydroxyethoxy)ethyl]piperazine,piperidine ethanol, 1-(2-hydroxyethyl)pyrrolidine,1-(2-hydroxyethyl)-2-pyrrolidinone, 3-piperidino-1,2-propanediol,3-pyrrolidino-1,2-propanediol, 8-hydroxyjulolidine, 3-quinuclidinol,3-tropanol, 1-methyl-2-pyrrolidine ethanol, 1-aziridine ethanol,N-(2-hydroxyethyl)phthalimide, and N-(2-hydroxyethyl)isonicotinamide.Examples of suitable amide derivatives include formamide,N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide,N,N-dimethylacetamide, propionamide, and benzamide. Suitable imidederivatives include phthalimide, succinimide, and maleimide.

In addition, basic compounds of the following general formula (B)-1 mayalso be included alone or in admixture.

N(X′)_(n′)(Y′)_(3-n′)  (B)-1

In the formula, n′ is equal to 1, 2 or 3; the side chain Y′ isindependently hydrogen or a straight, branched or cyclic C₁-C₂₀ alkylgroup which may contain a hydroxyl or ether group; and the side chain X′is independently selected from groups of the following general formulas(X′)-1 to (X′)-3, and two or three X′ may bond together to form a ring.

In the formulas, R³⁰⁰, R³⁰² and R³⁰⁵ are independently straight orbranched C₁-C₄ alkylene groups; R³⁰¹ and R³⁰⁴ are independently hydrogenor straight, branched or cyclic C₁-C₂₀ alkyl groups, which may containat least one hydroxyl group, ether group, ester group or lactone ring;R³⁰³ is a single bond or a straight or branched C₁-C₄ alkylene group;R³⁰⁶ is a straight, branched or cyclic C₁-C₂₀ alkyl group, which maycontain at least one hydroxyl group, ether group, ester group or lactonering.

Illustrative examples of the basic compounds of formula (B)-1 include

-   tris(2-methoxymethoxyethyl)amine,-   tris{2-(2-methoxyethoxy)ethyl}amine,-   tris{2-(2-methoxyethoxymethoxy)ethyl}amine,-   tris{2-(1-methoxyethoxy)ethyl}amine,-   tris{2-(1-ethoxyethoxy)ethyl}amine,-   tris{2-(1-ethoxypropoxy)ethyl}amine,-   tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine,-   4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane,-   4,7,13,18-tetraoxa-1,10-diazabicyclo[8.5.5]eicosane,-   1,4,10,13-tetraoxa-7,16-diazabicyclooctadecane,-   1-aza-12-crown-4,1-aza-15-crown-5,1-aza-18-crown-6,-   tris(2-formyloxyethyl)amine, tris(2-acetoxyethyl)amine,-   tris(2-propionyloxyethyl)amine, tris(2-butyryloxyethyl)amine,-   tris(2-isobutyryloxyethyl)amine, tris(2-valeryloxyethyl)amine,-   tris(2-pivaloyloxyethyl)amine,-   N,N-bis(2-acetoxyethyl)-2-(acetoxyacetoxy)ethylamine,-   tris(2-methoxycarbonyloxyethyl)amine,-   tris(2-tert-butoxycarbonyloxyethyl)amine,-   tris[2-(2-oxopropoxy)ethyl]amine,-   tris[2-(methoxycarbonylmethyl)oxyethyl]amine,-   tris[2-(tert-butoxycarbonylmethyloxy)ethyl]amine,-   tris[2-(cyclohexyloxycarbonylmethyloxy)ethyl]amine,-   tris(2-methoxycarbonylethyl)amine,-   tris(2-ethoxycarbonylethyl)amine,-   N,N-bis(2-hydroxyethyl)-2-(methoxycarbonyl)ethylamine,-   N,N-bis(2-acetoxyethyl)-2-(methoxycarbonyl)ethylamine,-   N,N-bis(2-hydroxyethyl)-2-(ethoxycarbonyl)ethylamine,-   N,N-bis(2-acetoxyethyl)-2-(ethoxycarbonyl)ethylamine,-   N,N-bis(2-hydroxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,-   N,N-bis(2-acetoxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine,-   N,N-bis(2-hydroxyethyl)-2-(2-hydroxyethoxycarbonyl)ethylamine,-   N,N-bis(2-acetoxyethyl)-2-(2-acetoxyethoxycarbonyl)ethylamine,-   N,N-bis(2-hydroxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine,-   N,N-bis(2-acetoxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine,-   N,N-bis(2-hydroxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,-   N,N-bis(2-acetoxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine,-   N,N-bis(2-hydroxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)-ethylamine,-   N,N-bis(2-acetoxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)-ethylamine,-   N,N-bis(2-hydroxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxy-carbonyl]ethylamine,-   N,N-bis(2-acetoxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxy-carbonyl]ethylamine,-   N,N-bis(2-hydroxyethyl)-2-(4-hydroxybutoxycarbonyl)ethylamine,-   N,N-bis(2-formyloxyethyl)-2-(4-formyloxybutoxycarbonyl)-ethylamine,-   N,N-bis(2-formyloxyethyl)-2-(2-formyloxyethoxycarbonyl)-ethylamine,-   N,N-bis(2-methoxyethyl)-2-(methoxycarbonyl)ethylamine,-   N-(2-hydroxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,-   N-(2-acetoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,-   N-(2-hydroxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,-   N-(2-acetoxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine,-   N-(3-hydroxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,-   N-(3-acetoxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine,-   N-(2-methoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine,-   N-butyl-bis[2-(methoxycarbonyl)ethyl]amine,-   N-butyl-bis[2-(2-methoxyethoxycarbonyl)ethyl]amine,-   N-methyl-bis(2-acetoxyethyl)amine,-   N-ethyl-bis(2-acetoxyethyl)amine,-   N-methyl-bis(2-pivaloyloxyethyl)amine,-   N-ethyl-bis[2-(methoxycarbonyloxy)ethyl]amine,-   N-ethyl-bis[2-(tert-butoxycarbonyloxy)ethyl]amine,-   tris(methoxycarbonylmethyl)amine,-   tris(ethoxycarbonylmethyl)amine,-   N-butyl-bis(methoxycarbonylmethyl)amine,-   N-hexyl-bis(methoxycarbonylmethyl)amine, and-   β-(diethylamino)-δ-valerolactone.

Also useful are one or more of cyclic structure-bearing basic compoundshaving the following general formula (B)-2.

Herein X′ is as defined above, and R³⁰⁷ is a straight or branched C₂-C₂₀alkylene group which may contain one or more carbonyl, ether, ester orsulfide groups.

Illustrative examples of the cyclic structure-bearing basic compoundshaving formula (B)-2 include

-   1-[2-(methoxymethoxy)ethyl]pyrrolidine,-   1-[2-(methoxymethoxy)ethyl]piperidine,-   4-[2-(methoxymethoxy)ethyl]morpholine,-   1-[2-[(2-methoxyethoxy)methoxy]ethyl]pyrrolidine,-   1-[2-[(2-methoxyethoxy)methoxy]ethyl]piperidine,-   4-[2-[(2-methoxyethoxy)methoxy]ethyl]morpholine,-   2-(1-pyrrolidinyl)ethyl acetate, 2-piperidinoethyl acetate,-   2-morpholinoethyl acetate, 2-(1-pyrrolidinyl)ethyl formate,-   2-piperidinoethyl propionate, 2-morpholinoethyl acetoxyacetate,-   2-(1-pyrrolidinyl)ethyl methoxyacetate,-   4-[2-(methoxycarbonyloxy)ethyl]morpholine,-   1-[2-(t-butoxycarbonyloxy)ethyl]piperidine,-   4-[2-(2-methoxyethoxycarbonyloxy)ethyl]morpholine,-   methyl 3-(1-pyrrolidinyl)propionate,-   methyl 3-piperidinopropionate, methyl 3-morpholinopropionate,-   methyl 3-(thiomorpholino)propionate,-   methyl 2-methyl-3-(1-pyrrolidinyl)propionate, ethyl    3-morpholinopropionate,-   methoxycarbonylmethyl 3-piperidinopropionate,-   2-hydroxyethyl 3-(1-pyrrolidinyl)propionate,-   2-acetoxyethyl 3-morpholinopropionate,-   2-oxotetrahydrofuran-3-yl 3-(1-pyrrolidinyl)propionate,    tetrahydrofurfuryl 3-morpholinopropionate,-   glycidyl 3-piperidinopropionate,-   2-methoxyethyl 3-morpholinopropionate,-   2-(2-methoxyethoxy)ethyl 3-(1-pyrrolidinyl)propionate,-   butyl 3-morpholinopropionate, cyclohexyl 3-piperidinopropionate,-   α-(1-pyrrolidinyl)methyl-γ-butyrolactone,-   β-piperidino-γ-butyrolactone, β-morpholino-δ-valerolactone, methyl    1-pyrrolidinylacetate, methyl piperidinoacetate, methyl    morpholinoacetate, methyl thiomorpholinoacetate, ethyl    1-pyrrolidinylacetate, and-   2-methoxyethyl morpholinoacetate.

Also, one or more of cyano-bearing basic compounds having the followinggeneral formulae (B)-3 to (B)-6 may be blended.

Herein, X′, R³⁰⁷ and n′ are as defined above, and R³⁰⁸ and R³⁰⁹ each areindependently a straight or branched C₁-C₄ alkylene group.

Illustrative examples of the cyano-bearing basic compounds havingformulae (B)-3 to (B)-6 include

-   3-(diethylamino)propiononitrile,-   N,N-bis(2-hydroxyethyl)-3-aminopropiononitrile,-   N,N-bis(2-acetoxyethyl)-3-aminopropiononitrile,-   N,N-bis(2-formyloxyethyl)-3-aminopropiononitrile,-   N,N-bis(2-methoxyethyl)-3-aminopropiononitrile,-   N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropiononitrile,-   methyl N-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropionate,-   methyl N-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropionate,-   methyl N-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropionate,-   N-(2-cyanoethyl)-N-ethyl-3-aminopropiononitrile,-   N-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropiononitrile,-   N-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropiononitrile,-   N-(2-cyanoethyl)-N-(2-formyloxyethyl)-3-aminopropiononitrile,-   N-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropiononitrile,-   N-(2-cyanoethyl)-N-[2-(methoxymethoxy)ethyl]-3-aminopropiono-nitrile,-   N-(2-cyanoethyl)-N-(3-hydroxy-1-propyl)-3-aminopropiononitrile,-   N-(3-acetoxy-1-propyl)-N-(2-cyanoethyl)-3-aminopropiononitrile,-   N-(2-cyanoethyl)-N-(3-formyloxy-1-propyl)-3-aminopropiono-nitrile,-   N-(2-cyanoethyl)-N-tetrahydrofurfuryl-3-aminopropiononitrile,-   N,N-bis(2-cyanoethyl)-3-aminopropiononitrile,-   diethylaminoacetonitrile,-   N,N-bis(2-hydroxyethyl)aminoacetonitrile,-   N,N-bis(2-acetoxyethyl)aminoacetonitrile,-   N,N-bis(2-formyloxyethyl)aminoacetonitrile,-   N,N-bis(2-methoxyethyl)aminoacetonitrile,-   N,N-bis[2-(methoxymethoxy)ethyl]aminoacetonitrile,-   methyl N-cyanomethyl-N-(2-methoxyethyl)-3-aminopropionate,-   methyl N-cyanomethyl-N-(2-hydroxyethyl)-3-aminopropionate,-   methyl N-(2-acetoxyethyl)-N-cyanomethyl-3-aminopropionate,-   N-cyanomethyl-N-(2-hydroxyethyl)aminoacetonitrile,-   N-(2-acetoxyethyl)-N-(cyanomethyl)aminoacetonitrile,-   N-cyanomethyl-N-(2-formyloxyethyl)aminoacetonitrile,-   N-cyanomethyl-N-(2-methoxyethyl)aminoacetonitrile,-   N-cyanomethyl-N-(2-(methoxymethoxy)ethyl)aminoacetonitrile,-   N-cyanomethyl-N-(3-hydroxy-1-propyl)aminoacetonitrile,-   N-(3-acetoxy-1-propyl)-N-(cyanomethyl)aminoacetonitrile,-   N-cyanomethyl-N-(3-formyloxy-1-propyl)aminoacetonitrile,-   N,N-bis(cyanomethyl)aminoacetonitrile,-   1-pyrrolidinepropiononitrile, 1-piperidinepropiononitrile,-   4-morpholinepropiononitrile, 1-pyrrolidineacetonitrile,-   1-piperidineacetonitrile, 4-morpholineacetonitrile,-   cyanomethyl 3-diethylaminopropionate,-   cyanomethyl N,N-bis(2-hydroxyethyl)-3-aminopropionate,-   cyanomethyl N,N-bis(2-acetoxyethyl)-3-aminopropionate,-   cyanomethyl N,N-bis(2-formyloxyethyl)-3-aminopropionate,-   cyanomethyl N,N-bis(2-methoxyethyl)-3-aminopropionate,-   cyanomethyl N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate,-   2-cyanoethyl 3-diethylaminopropionate,-   2-cyanoethyl N,N-bis(2-hydroxyethyl)-3-aminopropionate,-   2-cyanoethyl N,N-bis(2-acetoxyethyl)-3-aminopropionate,-   2-cyanoethyl N,N-bis(2-formyloxyethyl)-3-aminopropionate,-   2-cyanoethyl N,N-bis(2-methoxyethyl)-3-aminopropionate,-   2-cyanoethyl N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate,-   cyanomethyl 1-pyrrolidinepropionate,-   cyanomethyl 1-piperidinepropionate,-   cyanomethyl 4-morpholinepropionate,-   2-cyanoethyl 1-pyrrolidinepropionate,-   2-cyanoethyl 1-piperidinepropionate, and-   2-cyanoethyl 4-morpholinepropionate.

Also included are basic compounds as described in JP-A 2004-347736 andJP-A 2004-347738.

The basic compounds may be used alone or in admixture of two or more.The basic compound is preferably formulated in an amount of 0 to 2parts, and especially 0 to 1 part by weight, per 100 parts by weight ofthe base resin.

Component E

In one preferred embodiment, the resist composition further contains (E)a compound capable of generating an acid upon exposure to high-energyradiation (e.g., UV, deep UV, electron beam, x-ray, excimer laser beam,gamma-ray or synchrotron radiation), that is, an auxiliary photoacidgenerator other than component (A). Suitable auxiliary photoacidgenerators include sulfonium salts, iodonium salts,sulfonyldiazomethane, N-sulfonyloxydicarboxylmide, O-arylsulfonyloximeand O-alkylsulfonyloxime photoacid generators. Exemplary auxiliaryphotoacid generators are given below while they may be used alone or inadmixture of two or more.

Sulfonium salts are salts of sulfonium cations with sulfonates,bis(substituted alkylsulfonyl)imides and tris(substitutedalkylsulfonyl)methides. Exemplary sulfonium cations includetriphenylsulfonium, (4-tert-butoxyphenyl)diphenylsulfonium,bis(4-tert-butoxyphenyl)phenylsulfonium,tris(4-tert-butoxyphenyl)sulfonium,(3-tert-butoxyphenyl)diphenylsulfonium,bis(3-tert-butoxyphenyl)phenylsulfonium,tris(3-tert-butoxyphenyl)sulfonium,(3,4-di-tert-butoxyphenyl)diphenylsulfonium,bis(3,4-di-tert-butoxyphenyl)phenylsulfonium,tris(3,4-di-tert-butoxyphenyl)sulfonium,diphenyl(4-thiophenoxyphenyl)sulfonium,(4-tert-butoxycarbonylmethyloxyphenyl)diphenylsulfonium,tris(4-tert-butoxycarbonylmethyloxyphenyl)sulfonium,(4-tert-butoxyphenyl)bis(4-dimethylaminophenyl)sulfonium,tris(4-dimethylaminophenyl)sulfonium, 4-methylphenyldiphenylsulfonium,4-tert-butylphenyldiphenylsulfonium, bis(4-methylphenyl)phenylsulfonium,bis(4-tert-butylphenyl)phenylsulfonium, tris(4-methylphenyl)sulfonium,tris(4-tert-butylphenyl)sulfonium, tris(phenylmethyl)sulfonium,2-naphthyldiphenylsulfonium, dimethyl-2-naphthylsulfonium,4-hydroxyphenyldimethylsulfonium, 4-methoxyphenyldimethylsulfonium,trimethylsulfonium, 2-oxocyclohexylcyclohexylmethylsulfonium,trinaphthylsulfonium, tribenzylsulfonium, diphenylmethylsulfonium,dimethylphenylsulfonium, 2-oxopropylthiacyclopentanium,2-oxobutylthiacyclopentanium, 2-oxo-3,3-dimethylbutylthiacyclopentanium,2-oxo-2-phenylethylthiacyclopentanium,4-n-butoxynaphthyl-1-thiacyclopentanium, and2-n-butoxynaphthyl-1-thiacyclopentanium. Exemplary sulfonates includetrifluoromethanesulfonate, pentafluoroethanesulfonate,heptafluoropropanesulfonate, nonafluorobutanesulfonate,dodecafluorohexanesulfonate,pentafluoroethylperfluorocyclohexanesulfonate,heptadecafluorooctanesulfonate, perfluoro-4-ethylcyclohexanesulfonate,2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate,4-trifluoromethylbenzenesulfonate, 4-fluorobenzenesulfonate,mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate,toluenesulfonate, benzenesulfonate,4-(4′-toluenesulfonyloxy)benzenesulfonate,6-(4-toluenesulfonyloxy)naphthalene-2-sulfonate,4-(4-toluenesulfonyloxy)naphthalene-1-sulfonate,5-(4-toluenesulfonyloxy)naphthalene-1-sulfonate,8-(4-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, methanesulfonate,1,1-difluoro-2-naphthyl-ethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate, and1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonate.Exemplary bis(substituted alkylsulfonyl)imides includebistrifluoromethylsulfonylimide, bispentafluoroethylsulfonylimide,bisheptafluoropropylsulfonylimide, and 1,3-propylenebissulfonylimide. Atypical tris(substituted alkylsulfonyl)methide istristrifluoromethylsulfonylmethide. Sulfonium salts based on combinationof the foregoing examples are included.

Iodonium salts are salts of iodonium cations with sulfonates,bis(substituted alkylsulfonyl)imides and tris(substitutedalkylsulfonyl)methides. Exemplary iodonium cations are aryliodoniumcations including diphenyliodinium, bis(4-tert-butylphenyl)iodonium,4-tert-butoxyphenylphenyliodonium, and 4-methoxyphenylphenyliodonium.Exemplary sulfonates include trifluoromethanesulfonate,pentafluoroethanesulfonate, heptafluoropropanesulfonate,nonafluorobutanesulfonate, dodecafluorohexanesulfonate,pentafluoroethylperfluorocyclohexanesulfonate,heptadecafluorooctanesulfonate, perfluoro-4-ethylcyclohexanesulfonate,2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate,4-trifluoromethylbenzenesulfonate, 4-fluorobenzenesulfonate,mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate,toluenesulfonate, benzenesulfonate,4-(4′-toluenesulfonyloxy)benzenesulfonate,6-(4-toluenesulfonyloxy)naphthalene-2-sulfonate,4-(4-toluenesulfonyloxy)naphthalene-1-sulfonate,5-(4-toluenesulfonyloxy)naphthalene-1-sulfonate,8-(4-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate,camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate,butanesulfonate, methanesulfonate,1,1-difluoro-2-naphthyl-ethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate, and1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonate.Exemplary bis(substituted alkylsulfonyl)imides includebistrifluoromethylsulfonylimide, bispentafluoroethylsulfonylimide,bisheptafluoropropylsulfonylimide, and 1,3-propylenebissulfonylimide. Atypical tris(substituted alkylsulfonyl)methide istristrifluoromethylsulfonylmethide. Iodonium salts based on combinationof the foregoing examples are included.

Exemplary sulfonyldiazomethane compounds include bissulfonyldiazomethanecompounds and sulfonyl-carbonyldiazomethane compounds such asbis(ethylsulfonyl)diazomethane, bis(1-methylpropylsulfonyl)diazomethane,bis(2-methylpropylsulfonyl)diazomethane,bis(1,1-dimethylethylsulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,bis(perfluoroisopropylsulfonyl)diazomethane,bis(phenylsulfonyl)diazomethane,bis(4-methylphenylsulfonyl)diazomethane,bis(2,4-dimethylphenylsulfonyl)diazomethane,bis(4-acetyloxyphenylsulfonyl)diazomethane,bis(4-methanesulfonyloxyphenylsulfonyl)diazomethane,bis(4-(4-toluenesulfonyloxy)phenylsulfonyl)diazomethane,bis(2-naphthylsulfonyl)diazomethane,4-methylphenylsulfonylbenzoyldiazomethane,tert-butylcarbonyl-4-methylphenylsulfonyldiazomethane,2-naphthylsulfonylbenzoyldiazomethane,4-methylphenylsulfonyl-2-naphthoyldiazomethane,methylsulfonylbenzoyldiazomethane, andtert-butoxycarbonyl-4-methylphenylsulfonyldiazomethane.

N-sulfonyloxydicarboxylmide photoacid generators include combinations ofimide skeletons with sulfonates. Exemplary imide skeletons aresuccinimide, naphthalenedicarboxylmide, phthalimide,cyclohexyldicarboxylmide, 5-norbornene-2,3-dicarboxylmide, and7-oxabicyclo[2.2.1]-5-heptene-2,3-dicarboxylmide. Exemplary sulfonatesinclude trifluoromethanesulfonate, pentafluoroethanesulfonate,heptafluoropropanesulfonate, nonafluorobutanesulfonate,dodecafluorohexanesulfonate,pentafluoroethylperfluorocyclohexanesulfonate,heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate,pentafluorobenzenesulfonate, 4-trifluoromethylbenzenesulfonate,4-fluorobenzenesulfonate, mesitylenesulfonate,2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate,naphthalenesulfonate, camphorsulfonate, octanesulfonate,dodecylbenzenesulfonate, butanesulfonate, methanesulfonate,1,1-difluoro-2-naphthyl-ethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate, and1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonate.

Benzoinsulfonate photoacid generators include benzoin tosylate, benzoinmesylate, and benzoin butanesulfonate.

Pyrogallol trisulfonate photoacid generators include pyrogallol,fluoroglycine, catechol, resorcinol, hydroquinone, in which all thehydroxyl groups are substituted by trifluoromethanesulfonate,pentafluoroethanesulfonate, heptafluoropropanesulfonate,nonafluorobutanesulfonate, dodecafluorohexanesulfonate,pentafluoroethylperfluorocyclohexanesulfonate,heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate,pentafluorobenzenesulfonate, 4-trifluoromethylbenzenesulfonate,4-fluorobenzenesulfonate, toluenesulfonate, benzenesulfonate,naphthalenesulfonate, camphorsulfonate, octanesulfonate,dodecylbenzenesulfonate, butanesulfonate, methanesulfonate,1,1-difluoro-2-naphthyl-ethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate,1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonateor the like.

Nitrobenzyl sulfonate photoacid generators include 2,4-dinitrobenzylsulfonate, 2-nitrobenzyl sulfonate, and 2,6-dinitrobenzyl sulfonate,with exemplary sulfonates including trifluoromethanesulfonate,pentafluoroethanesulfonate, heptafluoropropanesulfonate,nonafluorobutanesulfonate, dodecafluorohexanesulfonate,pentafluoroethylperfluorocyclohexanesulfonate,heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate,pentafluorobenzenesulfonate, 4-trifluoromethylbenzenesulfonate,4-fluorobenzenesulfonate, toluenesulfonate, benzenesulfonate,naphthalenesulfonate, camphorsulfonate, octanesulfonate,dodecylbenzenesulfonate, butanesulfonate, methanesulfonate,1,1-difluoro-2-naphthyl-ethanesulfonate,1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate,1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-en-8-yl)ethanesulfonate.Also useful are analogous nitrobenzyl sulfonate compounds in which thenitro group on the benzyl side is substituted by a trifluoromethylgroup.

Sulfone photoacid generators include bis(phenylsulfonyl)methane,bis(4-methylphenylsulfonyl)methane, bis(2-naphthylsulfonyl)methane,2,2-bis(phenylsulfonyl)propane, 2,2-bis(4-methylphenylsulfonyl)propane,2,2-bis(2-naphthylsulfonyl)propane,2-methyl-2-(p-toluenesulfonyl)propiophenone,2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane, and2,4-dimethyl-2-(p-toluenesulfonyl)pentan-3-one.

Suitable O-arylsulfonyloxime compounds and O-alkylsulfonyloximecompounds (oxime sulfonates) include photoacid generators in the form ofglyoxime derivatives (as described in Japanese Patent No. 2,906,999 andJP-A 9-301948); photoacid generators in the form of oxime sulfonateswith a long conjugated system separated by thiophene or cyclohexadiene(as described in U.S. Pat. No. 6,004,724); oxime sulfonates having anelectron withdrawing group such as trifluoromethyl incorporated forincreased stability (as described in U.S. Pat. No. 6,261,738, JP-A2000-314956, International Publication No. 2004-074242); oximesulfonates using phenylacetonitrile or substituted acetonitrilederivatives (as described in JP-A 9-95479, JP-A 9-230588 and thecompounds described in the prior art section thereof); and bisoximesulfonates (as described in JP-A 9-208554, GB 2348644A, JP-A2002-278053).

When the photoacid generator (E) is added to the KrF excimer laserresist composition, preference is given to sulfonium salts,bissulfonyldiazomethanes, N-sulfonyloxydicarboxylmides and oximesulfonates. Illustrative preferred photoacid generators includetriphenylsulfonium p-toluenesulfonate, triphenylsulfoniumcamphorsulfonate, triphenylsulfonium pentafluorobenzenesulfonate,triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfonium4-(4′-toluenesulfonyloxy)benzenesulfonate, triphenylsulfonium2,4,6-triisopropylbenzenesulfonate, 4-tert-butoxyphenyldiphenylsulfoniump-toluenesulfonate, 4-tert-butoxyphenyldiphenylsulfoniumcamphorsulfonate, 4-tert-butoxyphenyldiphenylsulfonium4-(4′-toluenesulfonyl-oxy)benzenesulfonate,tris(4-methylphenyl)sulfonium camphorsulfonate,tris(4-tert-butylphenyl)sulfonium camphorsulfonate,bis(tert-butylsulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,bis(2,4-dimethylphenylsulfonyl)diazomethane,bis(4-tert-butylphenylsulfonyl)diazomethane,N-camphorsulfonyloxy-5-norbornene-2,3-carboxylic acid imide,N-p-toluenesulfonyloxy-5-norbornene-2,3-carboxylic acid imide,(5-(10-camphorsulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile,and(5-(4-toluenesulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile.

When the photoacid generator (E) is added to the ArF laser resistcomposition, preference is given to sulfonium salts and oximesulfonates. Illustrative preferred photoacid generators includetriphenylsulfonium trifluoromethanesulfonate, triphenylsulfoniumnonafluorobutanesulfonate, diphenyl-4-methylphenylsulfoniumnonafluorobutanesulfonate, 2-oxo-2-phenylethylthiacyclopentaniumnonafluorobutanesulfonate, triphenylsulfoniumperfluoro-4-ethylcyclohexanesulfonate,4-tert-butylphenyldiphenylsulfonium nonafluorobutanesulfonate,4-tert-butylphenyldiphenylsulfonium heptadecafluorooctane-sulfonate, and2,2,3,3,4,4,5,5,6,6,7,7-decafluoro-1-(2-fluorenyl)heptanone-oximeperfluoro-1-butanesulfonate.

When the photoacid generator (E) is added to the ArF immersionlithography resist composition, preference is given to sulfonium saltsand oxime sulfonates. Illustrative preferred photoacid generatorsinclude triphenylsulfonium nonafluorobutanesulfonate,diphenyl-4-methylphenylsulfonium nonafluorobutanesulfonate,triphenylsulfonium perfluoro-4-ethylcyclohexanesulfonate,4-tert-butylphenyldiphenylsulfonium nonafluorobutanesulfonate,4-tert-butylphenyldiphenylsulfonium heptadecafluorooctane-sulfonate, and2,2,3,3,4,4,5,5,6,6,7,7-decafluoro-1-(2-fluorenyl)heptanone-oximeperfluoro-1-butanesulfonate.

In the chemically amplified resist composition comprising the photoacidgenerator capable of generating the sulfonic acid of formula (Ia) as thefirst photoacid generator (A) according to the invention, the auxiliaryphotoacid generator (E) may be used in any desired amount as long as itdoes not compromise the effects of the invention. An appropriate amountof the auxiliary photoacid generator (E) is 0 to 10 parts, andespecially 0 to 5 parts by weight per 100 parts by weight of the baseresin in the composition. Too high a proportion of the auxiliaryphotoacid generator (E) may give rise to problems of degraded resolutionand foreign matter upon development and resist film peeling. Theauxiliary photoacid generators may be used alone or in admixture of twoor more. The transmittance of the resist film can be controlled by usingan (auxiliary) photoacid generator having a low transmittance at theexposure wavelength and adjusting the amount of the photoacid generatoradded.

In the resist composition of the invention, there may be added acompound which is decomposed with an acid to generate another acid, thatis, acid amplifier compound. For these compounds, reference should bemade to J. Photopolym. Sci. and Tech., 8, 43-44, 45-46 (1995), andibid., 9, 29-30 (1996).

Examples of the acid amplifier compound includetert-butyl-2-methyl-2-tosyloxymethyl acetoacetate and2-phenyl-2-(2-tosyloxyethyl)-1,3-dioxolane, but are not limited thereto.Of well-known photoacid generators, many of those compounds having poorstability, especially poor thermal stability exhibit an acidamplifier-like behavior.

In the resist composition of the invention, an appropriate amount of theacid amplifier compound is up to 2 parts, and especially up to 1 part byweight per 100 parts by weight of the base resin. Excessive amounts ofthe acid amplifier compound make diffusion control difficult, leading todegradation of resolution and pattern profile.

Component F

Component (F) is an organic acid derivative and/or a fluorinatedalcohol.

Illustrative, non-limiting, examples of the organic acid derivativesinclude phenol, cresol, catechol, resorcinol, pyrogallol, fluoroglycin,bis(4-hydroxyphenyl)methane, 2,2-bis(4′-hydroxyphenyl)propane,bis(4-hydroxyphenyl)sulfone, 1,1,1-tris(4′-hydroxyphenyl)ethane,1,1,2-tris(4′-hydroxyphenyl)ethane, hydroxybenzophenone,4-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid,2-hydroxyphenylacetic acid, 3-(4-hydroxyphenyl)propionic acid,3-(2-hydroxyphenyl)propionic acid, 2,5-dihydroxyphenylacetic acid,3,4-dihydroxyphenylacetic acid, 1,2-phenylenediacetic acid,1,3-phenylenediacetic acid, 1,4-phenylenediacetic acid,1,2-phenylenedioxydiacetic acid, 1,4-phenylenedipropanoic acid, benzoicacid, salicylic acid, 4,4-bis(4′-hydroxyphenyl)valeric acid,4-tert-butoxyphenylacetic acid, 4-(4-hydroxyphenyl)butyric acid,3,4-dihydroxymandelic acid, and 4-hydroxymandelic acid. Of these;salicylic acid and 4,4-bis(4′-hydroxyphenyl)valeric acid are preferred.They may be used alone or in admixture of two or more.

The fluorinated alcohol is an alcohol which is substituted with fluorineatoms except α-position. Those compounds terminated with1,1,1,3,3,3-hexafluoro-2-propanol are desirable although the fluorinatedalcohols are not limited thereto. Illustrative examples of the desirablefluorinated alcohols are given below.

Note that R″ is selected from C₂-C₃₀ acetal groups and tertiaryl alkylgroups having formulae (C1) and (C2) which have been described in the“base resin” section.

In the chemically amplified resist composition of the invention, theorganic acid derivative or fluorinated alcohol is preferably formulatedin an amount of up to 5 parts, and especially up to 1 part by weight,per 100 parts by weight of the base resin. More than 5 parts wouldresult in too low a resolution. Depending on the combination of theother components in the resist composition, the organic acid derivativeand fluorinated alcohol may be omitted.

Component G

In one preferred embodiment, the resist composition further contains (G)a compound with a weight average molecular weight of up to 3,000 whichchanges its solubility in an alkaline developer under the action of anacid, that is, a dissolution inhibitor. Typically, a compound obtainedby substituting acid labile substituents for some or all hydrogen atomsof hydroxyl groups on a phenol or carboxylic acid derivative having alow molecular weight of up to 2,500 or fluorinated alcohol is added asthe dissolution inhibitor.

Examples of the phenol or carboxylic acid derivative having a molecularweight of up to 2,500 include bisphenol A, bisphenol H, bisphenol S,4,4-bis(4′-hydroxyphenyl)valeric acid, tris(4-hydroxyphenyl)methane,1,1,1-tris(4′-hydroxyphenyl)ethane, 1,1,2-tris(4′-hydroxyphenyl)ethane,phenolphthalein, thymolphthalein, cholic acid, deoxycholic acid, andlithocholic acid. Examples of the fluorinated alcohol are as describedabove for component (F). The acid labile substituents are the same asthose exemplified as the acid labile groups in the polymer.

Illustrative, non-limiting, examples of the dissolution inhibitors whichare useful herein include bis(4-(2′-tetrahydropyranyloxy)phenyl)methane,bis(4-(2′-tetrahydrofuranyloxy)phenyl)methane,bis(4-tert-butoxyphenyl)methane,bis(4-tert-butoxycarbonyloxyphenyl)methane,bis(4-tert-butoxycarbonylmethyloxyphenyl)methane,bis(4-(1′-ethoxyethoxy)phenyl)methane,bis(4-(1′-ethoxypropyloxy)phenyl)methane,2,2-bis(4′-(2″-tetrahydropyranyloxy))propane,2,2-bis(4′-(2″-tetrahydrofuranyloxy)phenyl)propane,2,2-bis(4′-tert-butoxyphenyl)propane,2,2-bis(4′-tert-butoxycarbonyloxyphenyl)propane,2,2-bis(4-tert-butoxycarbonylmethyloxyphenyl)propane,2,2-bis(4′-(1″-ethoxyethoxy)phenyl)propane,2,2-bis(4′-(1″-ethoxypropyloxy)phenyl)propane, tert-butyl4,4-bis(4′-(2″-tetrahydropyranyloxy)phenyl)-valerate, tert-butyl4,4-bis(4′-(2″-tetrahydrofuranyloxy)phenyl)-valerate, tert-butyl4,4-bis(4′-tert-butoxyphenyl)valerate, tert-butyl4,4-bis(4-tert-butoxycarbonyloxyphenyl)valerate, tert-butyl4,4-bis(4′-tert-butoxycarbonylmethyloxyphenyl)-valerate, tert-butyl4,4-bis(4′-(1″-ethoxyethoxy)phenyl)valerate, tert-butyl4,4-bis(4′-(1″-ethoxypropyloxy)phenyl)valerate,tris(4-(2′-tetrahydropyranyloxy)phenyl)methane,tris(4-(2′-tetrahydrofuranyloxy)phenyl)methane,tris(4-tert-butoxyphenyl)methane,tris(4-tert-butoxycarbonyloxyphenyl)methane,tris(4-tert-butoxycarbonyloxymethylphenyl)methane,tris(4-(1′-ethoxyethoxy)phenyl)methane,tris(4-(1′-ethoxypropyloxy)phenyl)methane,1,1,2-tris(4′-(2′-tetrahydropyranyloxy)phenyl)ethane,1,1,2-tris(4′-(2″-tetrahydrofuranyloxy)phenyl)ethane,1,1,2-tris(4′-tert-butoxyphenyl)ethane,1,1,2-tris(4′-tert-butoxycarbonyloxyphenyl)ethane,1,1,2-tris(4′-tert-butoxycarbonylmethyloxyphenyl)ethane,1,1,2-tris(4′-(1′-ethoxyethoxy)phenyl)ethane,1,1,2-tris(4′-(1′-ethoxypropyloxy)phenyl)ethane, tert-butyl cholate,tert-butyl deoxycholate, and tert-butyl lithocholate. The compoundsdescribed in JP-A 2003-107706 are also useful.

In the resist composition of the invention, an appropriate amount of thedissolution inhibitor (G) is up to 20 parts, and especially up to 15parts by weight per 100 parts by weight of the base resin. With morethan 20 parts of the dissolution inhibitor, the resist compositionbecomes less heat resistant because of an increased content of monomercomponents.

Component C′

The base resin used in the negative working resist composition is (C′) abase resin which is normally alkali soluble, but becomes substantiallyalkali insoluble under the action of a crosslinker. It is preferably aprecursor resin which will be substituted with acid labile groups toform the base resin (C).

Examples of the alkali-soluble resin include poly(p-hydroxystyrene),poly(m-hydroxystyrene), poly(4-hydroxy-2-methylstyrene),poly(4-hydroxy-3-methylstyrene), poly(α-methyl-p-hydroxystyrene),partially hydrogenated p-hydroxystyrene copolymers,p-hydroxystyrene-α-methyl-p-hydroxystyrene copolymers,p-hydroxystyrene-α-methylstyrene copolymers, p-hydroxystyrene-styrenecopolymers, p-hydroxystyrene-m-hydroxystyrene copolymers,p-hydroxystyrene-styrene copolymers, p-hydroxystyrene-acrylic acidcopolymers, p-hydroxystyrene-methacrylic acid copolymers,p-hydroxystyrene-methyl methacrylate copolymers,p-hydroxystyrene-acrylic acid-methyl methacrylate copolymers,p-hydroxystyrene-methyl acrylate copolymers,p-hydroxystyrene-methacrylic acid-methyl methacrylate copolymers,poly(methacrylic acid), poly(acrylic acid), acrylic acid-methyl acrylatecopolymers, methacrylic acid-methyl methacrylate copolymers, acrylicacid-maleimide copolymers, methacrylic acid-maleimide copolymers,p-hydroxystyrene-acrylic acid-maleimide copolymers, andp-hydroxystyrene-methacrylic acid-maleimide copolymers, but are notlimited to these combinations.

To impart a certain function, suitable substituent groups may beintroduced into some of the phenolic hydroxyl and carboxyl groups on theforegoing polymer (to be protected with acid labile groups). Exemplaryand preferred are substituent groups for improving adhesion to thesubstrate, substituent groups for improving etching resistance, andespecially substituent groups which are relatively stable against acidand alkali and effective for controlling such that the dissolution ratein an alkali developer of unexposed and low exposed areas of a resistfilm may not become too high. Illustrative, non-limiting, substituentgroups include 2-hydroxyethyl, 2-hydroxypropyl, methoxymethyl,methoxycarbonyl, ethoxycarbonyl, methoxycarbonylmethyl,ethoxycarbonylmethyl, 4-methyl-2-oxo-4-oxolanyl,4-methyl-2-oxo-4-oxanyl, methyl, ethyl, n-propyl, isopropyl, n-butyl,sec-butyl, acetyl, pivaloyl, adamantyl, isoboronyl, and cyclohexyl. Itis also possible to introduce acid-decomposable substituent groups suchas tert-butoxycarbonyl and relatively acid-undecomposable substituentgroups such as tert-butyl and tert-butoxycarbonylmethyl.

In the resist composition, the resin (C′) is blended in any desiredamount, preferably of 65 to 99 parts by weight, especially 65 to 98parts by weight per 100 parts by weight of the total amount of the solidmatters except the solvent.

Component H

Formulated in the negative resist composition is a crosslinker (F) whichforms a crosslinked structure under the action of acid. Typicalcrosslinkers are compounds having at least two hydroxymethyl,alkoxymethyl, epoxy or vinyl ether groups within a molecule. Substitutedglycoluril derivatives, urea derivatives, andhexa(methoxymethyl)melamine compounds are suitable as the crosslinker.Examples include N,N,N′,N′-tetramethoxymethylurea,hexamethoxymethylmelamine, tetraalkoxymethyl-substituted glycolurilcompounds such as tetrahydroxymethyl-substituted glycoluril andtetramethoxymethylglycoluril, and condensates of phenolic compounds suchas substituted or unsubstituted bis(hydroxymethylphenol) compounds andbisphenol A with epichlorohydrin. Especially preferred crosslinkers are1,3,5,7-tetraalkoxymethylglycolurils such as1,3,5,7-tetramethoxymethylglycoluril,1,3,5,7-tetrahydroxymethylglycoluril, 2,6-dihydroxymethyl-p-cresol,2,6-dihydroxymethylphenol, 2,2′,6,6′-tetrahydroxymethylbisphenol A,1,4-bis[2-(2-hydroxypropyl)]benzene, N,N,N′,N′-tetramethoxymethylurea,and hexamethoxymethylmelamine.

In the resist composition, an appropriate amount of the crosslinker is,though not limited thereto, about 1 to 20 parts, and especially about 5to 15 parts by weight per 100 parts by weight of the base resin. Thecrosslinkers may be used alone or in admixture of two or more.

In the chemically amplified resist composition of the invention, theremay be added such additives as a surfactant for improving coatingcharacteristics, and a light absorbing agent for reducing diffusereflection from the substrate.

Illustrative, non-limiting, examples of the surfactant include nonionicsurfactants, for example, polyoxyethylene alkyl ethers such aspolyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether,polyoxyethylene alkylaryl ethers such as polyoxyethylene octylphenolether and polyoxyethylene nonylphenol ether, polyoxyethylenepolyoxypropylene block copolymers, sorbitan fatty acid esters such assorbitan monolaurate, sorbitan monopalmitate, and sorbitan monostearate,and polyoxyethylene sorbitan fatty acid esters such as polyoxyethylenesorbitan monolaurate, polyoxyethylene sorbitan monopalmitate,polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitantrioleate, and polyoxyethylene sorbitan tristearate; fluorochemicalsurfactants such as EFTOP EF301, EF303 and EF352 (JEMCO Inc.), MegafaceF171, F172, F173, R08 and R30 (Dai-Nippon Ink & Chemicals, Inc.),Fluorad FC430, FC431, FC-4430 and FC-4432 (Sumitomo 3M Co., Ltd.),Aashiguard AG710, Surflon S-381, S-382, SC101, SC102, SC103, SC104,SC105, SC106, Surfynol E1004, KH-10, KH-20, KH-30 and KH-40 (Asahi GlassCo., Ltd.); organosiloxane polymers KP341, X-70-092 and X-70-093(Shin-Etsu Chemical Co., Ltd.), acrylic acid or methacrylic acidPolyflow No. 75 and No. 95 (Kyoeisha Ushi Kagaku Kogyo Co., Ltd.). Interalia, FC430, Surflon S-381, Surfynol E1004, KH-20 and KH-30 arepreferred. These surfactants may be used alone or in admixture.

In the chemically amplified resist composition of the invention, thesurfactant is preferably formulated in an amount of up to 2 parts, andespecially up to 1 part by weight, per 100 parts by weight of the baseresin.

In the chemically amplified resist composition of the invention, a UVabsorber may be added. Those UV absorbers described in JP-A 11-190904are useful, but the invention is not limited thereto. Exemplary UVabsorbers are diaryl sulfoxide derivatives such asbis(4-hydroxyphenyl)sulfoxide, bis(4-tert-butoxyphenyl)sulfoxide,bis(4-tert-butoxycarbonyloxyphenyl)sulfoxide, andbis[4-(1-ethoxyethoxy)phenyl]sulfoxide; diarylsulfone derivatives suchas bis(4-hydroxyphenyl)sulfone, bis(4-tert-butoxyphenyl)sulfone,bis(4-tert-butoxycarbonyloxyphenyl)sulfone,bis[4-(1-ethoxyethoxy)phenyl]sulfone, andbis[4-(1-ethoxypropoxy)phenyl]sulfone; diazo compounds such asbenzoquinonediazide, naphthoquinonediazide, anthraquinonediazide,diazofluorene, diazotetralone, and diazophenanthrone; quinonediazidogroup-containing compounds such as complete or partial ester compoundsbetween naphthoquinone-1,2-diazido-5-sulfonic acid chloride and2,3,4-trihydroxybenzophenone and complete or partial ester compoundsbetween naphthoquinone-1,2-diazido-4-sulfonic acid chloride and2,4,4′-trihydroxybenzophenone; tert-butyl 9-anthracenecarboxylate,tert-amyl 9-anthracenecarboxylate, tert-methoxymethyl9-anthracenecarboxylate, tert-ethoxyethyl 9-anthracenecarboxylate,2-tert-tetrahydropyranyl 9-anthracenecarboxylate, and2-tert-tetrahydrofuranyl 9-anthracenecarboxylate.

The UV absorber may or may not be added to the resist compositiondepending on the type of resist composition. An appropriate amount of UVabsorber, if added, is 0 to 10 parts, more preferably 0.5 to 10 parts,most preferably 1 to 5 parts by weight per 100 parts by weight of thebase resin.

For the microfabrication of integrated circuits, any well-knownlithography may be used to form a resist pattern from the chemicallyamplified resist composition of the invention.

The composition is applied onto a substrate (e.g., Si, SiO₂, SiN, SiON,TiN, WSi, BPSG, SOG, organic anti-reflective film, etc.) formicrofabrication by a suitable coating technique such as spin coating,roll coating, flow coating, dip coating, spray coating or doctorcoating. The coating is prebaked on a hot plate at a temperature of 60to 150° C. for about 1 to 10 minutes, preferably 80 to 120° C. for 1 to5 minutes. The resulting resist film is generally 0.1 to 2.0 μm thick.Through a photomask having a desired pattern, the resist film is thenexposed to radiation, preferably having an exposure wavelength of up to300 nm, such as UV, deep-UV, electron beam, x-ray, excimer laser light,γ-ray and synchrotron radiation. The preferred light source is a beamfrom an excimer laser, especially KrF excimer laser, deep UV of 245-255nm wavelength and ArF excimer laser. The exposure dose is preferably inthe range of about 1 to 200 mJ/cm², more preferably about 10 to 100mJ/cm². The film is further baked on a hot plate at 60 to 150° C. for 1to 5 minutes, preferably 80 to 140° C. for 1 to 3 minutes (post-exposurebaking=PEB).

Thereafter the resist film is developed with a developer in the form ofan aqueous base solution, for example, 0.1 to 5 wt %, preferably 2 to 3wt % aqueous solution of tetramethylammonium hydroxide (TMAH) for 0.1 to3 minutes, preferably 0.5 to 2 minutes by conventional techniques suchas dip, puddle or spray technique. In this way, a desired resist patternis formed on the substrate. It is appreciated that the resistcomposition of the invention is best suited for micro-patterning usingsuch actinic radiation as deep UV with a wavelength of 254 to 193 nm,vacuum UV with a wavelength of 157 nm, electron beam, x-ray, excimerlaser light, γ-ray and synchrotron radiation. With any of theabove-described parameters outside the above-described range, theprocess may sometimes fail to produce the desired pattern.

In the practice of the invention, the immersion lithography process ofusing ArF excimer laser of 193 nm wavelength and feeding a liquid suchas water, glycerin or ethylene glycol between the wafer and theprojection lens is advantageously applicable.

EXAMPLE

Synthesis Examples, Examples and Comparative Examples are given belowfor further illustrating the invention, but they are not to be construedas limiting the invention.

Synthesis Example 1 Synthesis of Triphenylsulfonium Chloride

Diphenyl sulfoxide, 40 g (0.2 mole), was dissolved in 400 g ofdichloroethane, which was stirred under ice cooling. At a temperaturebelow 20° C., 65 g (0.6 mole) of trimethylsilyl chloride was addeddropwise to the solution, which was aged for 30 minutes at thetemperature. Then, a Grignard reagent which had been prepared from 14.6g (0.6 mole) of metallic magnesium, 67.5 g (0.6 mole) of chlorobenzeneand 168 g of tetrahydrofuran (THF) was added dropwise at a temperaturebelow 20° C. The reaction solution was aged for one hour, after which 50g of water at a temperature below 20° C. was added to quench thereaction. To this solution, 150 g of water, 10 g of 12N hydrochloricacid, and 200 g of diethyl ether were further added.

The water layer was separated and washed with 100 g of diethyl ether,yielding an aqueous solution of triphenylsulfonium chloride. Thecompound in aqueous solution form was used in the subsequent reactionwithout further isolation.

Synthesis Example 2 Synthesis of 4-tert-butylphenyldiphenylsulfoniumbromide

The target compound was obtained by following the procedure of SynthesisExample 1 aside from using 4-tert-butylbromobenzene instead of thechlorobenzene in Synthesis Example 1 and increasing the amount of waterfor extraction.

Synthesis Example 3 Synthesis of 4-tert-butoxyphenyldiphenylsulfoniumchloride

The target compound was obtained by following the procedure of SynthesisExample 1 aside from using 4-tert-butoxychlorobenzene instead of thechlorobenzene in Synthesis Example 1, using dichloromethane containing 5wt % of triethylamine as the solvent, and increasing the amount of waterfor extraction.

Synthesis Example 4 Synthesis of tris(4-methylphenyl)sulfonium chloride

The target compound was obtained by following the procedure of SynthesisExample 1 aside from using bis(4-methylphenyl)sulfoxide instead of thediphenyl sulfoxide and 4-chlorotoluene instead of the chlorobenzene inSynthesis Example 1, and increasing the amount of water for extraction.

Synthesis Example 5 Synthesis of tris(4-tert-butylphenyl)sulfoniumbromide

The target compound was obtained by following the procedure of SynthesisExample 1 aside from using bis(4-tert-butylphenyl)sulfoxide instead ofthe diphenyl sulfoxide and 4-tert-butylbromobenzene instead of thechlorobenzene in Synthesis Example 1, and increasing the amount of waterfor extraction.

Synthesis Example 6 Synthesis of bis(4-tert-butylphenyl)iodoniumhydrogen sulfate

A mixture of 84 g (0.5 mole) of tert-butylbenzene, 53 g (0.25 mole) ofpotassium iodate and 50 g of acetic anhydride was stirred under icecooling, and a mixture of 35 g of acetic anhydride and 95 g of conc.sulfuric acid was added dropwise at a temperature below 30° C. Theresulting solution was aged for 3 hours at room temperature and icecooled again, after which 250 g of water was added dropwise to quenchthe reaction. The reaction solution was extracted with 400 g ofdichloromethane. The organic layer was discolored by adding 6 g ofsodium hydrogen sulfite. The organic layer was washed with 250 g ofwater three times. The washed organic layer was concentrated in vacuum,obtaining a crude target product. The product was used in the subsequentreaction without further purification.

Synthesis Example 7 Synthesis of Phenacyltetrahydrothiophenium Bromide

88.2 g (0.44 mole) of phenacyl bromide and 39.1 g (0.44 mole) oftetrahydrothiophene were dissolved in 220 g of nitromethane, which wasstirred for 4 hours at room temperature. 800 g of water and 400 g ofdiethyl ether were added to the reaction solution whereupon the mixtureseparated into two layers. The aqueous layer was taken out, which was anaqueous solution of the target compound, phenacyltetrahydrothiopheniumbromide.

Synthesis Example 8 Synthesis of Dimethylphenylsulfonium HydrogenSulfate

6.2 g (0.05 mole) of thioanisole and 6.9 g (0.055 mole) of dimethylsulfate were stirred for 12 hours at room temperature. 100 g of waterand 50 ml of diethyl ether were added to the reaction solution whereuponthe mixture separated into two layers. The aqueous layer was taken out,which was an aqueous solution of the target compound,dimethylphenylsulfonium hydrogen sulfate.

Synthesis Example 9 Synthesis of sodium1,1,3,3,3-pentafluoro-2-benzoyloxy-propane-1-sulfonate (Anion 1)

10.0 g of 1,1,3,3,3-pentafluoropropen-2-yl benzoate which had beensynthesized by a conventional technique, was dispersed in 72 g of water,after which 12.0 g of sodium hydrogen sulfite and 1.24 g of benzoylperoxide were added. Reaction occurred at 85° C. for 65 hours. Thereaction solution was allowed to cool, after which toluene was added,followed by separatory operation to separate a water layer. A saturatedsodium chloride aqueous solution was added to the water layer whereuponwhite crystals settled out. The crystals were collected by filtration,washed with a small volume of saturated sodium chloride aqueous solutionand then dried in vacuum, obtaining the target compound, sodium1,1,3,3,3-pentafluoro-2-benzoyloxypropane-1-sulfonate. White crystals,5.85 g (yield 43%).

The target compound was analyzed by spectroscopy. The data of infraredabsorption spectroscopy are shown below. The spectra of nuclear magneticresonance spectroscopy (¹H-NMR and ¹⁹F-NMR/D₂O) are shown in FIGS. 1 and2.

Infrared absorption spectra (IR; KBr disc, cm⁻¹)

-   -   1752, 1643, 1604, 1454, 1367, 1344, 1286, 1245, 1189, 1159,        1114, 1097, 1041, 1024, 1002, 908, 707, 647

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   NEGATIVE M⁻333 (corresponding to CF₃CH(OCOC₆H₅)CF₂SO₃ ⁻)

Synthesis Example 10 Synthesis of sodium1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate (Anion 2)

The target sodium sulfonate was obtained by following the procedure ofSynthesis Example 9 aside from using1,1,3,3,3-pentafluoropropen-2-yl-4-phenyl benzoate which had beensynthesized by a conventional technique.

Synthesis Example 11 Synthesis of triphenylsulfonium1,1,3,3,3-pentafluoro-2-benzoyloxypropane-1-sulfonate (PAG1)

To 50 g of dichloromethane were added an amount (corresponding to 0.011mole) of the triphenylsulfonium chloride aqueous solution of SynthesisExample 1 and 3.6 g (0.01 mole) of sodium1,1,3,3,3-pentafluoro-2-benzoyloxy-propane-1-sulfonate synthesized inSynthesis Example 9, followed by stirring. The organic layer wasseparated and washed with 50 g of water three times. The organic layerwas concentrated and 25 g of diethyl ether was added to the residue forcrystallization. The crystals were filtered and dried, obtaining thetarget compound. White crystals, 4.5 g (yield 75%).

The target compound was analyzed by spectroscopy. The data of IRspectroscopy are shown below. The NMR spectra (¹H-NMR and¹⁹F-NMR/DMSO-d₆) are shown in FIGS. 3 and 4.

Infrared absorption spectra (IR; KBr disc, cm⁻¹)

-   -   3085, 3064, 1739, 1600, 1477, 1448, 1375, 1328, 1215, 1192,        1167, 1109, 1072, 1043, 1022, 995, 939, 904, 840, 802, 754, 746,        713, 684, 640, 621, 574, 552, 503

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   POSITIVE M⁺263 (corresponding to (C₆H₅)₃S⁺)    -   NEGATIVE M⁻333 (corresponding to CF₃CH(OCOC₆H₅)CF₂SO₃ ⁻)

Synthesis Example 12 Synthesis of triphenylsulfonium1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate (PAG2)

The target compound was obtained by following the procedure of SynthesisExample 11 aside from using sodium1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propane-1-sulfonate,obtained in Synthesis Example 10, instead of the sodium1,1,3,3,3-pentafluoro-2-benzoyloxypropane-1-sulfonate used in SynthesisExample 11.

The target compound was analyzed by spectroscopy. The data of IRspectroscopy are shown below. The NMR spectra (¹H-NMR and¹⁹F-NMR/DMSO-d₆) are shown in FIGS. 5 and 6.

Infrared absorption spectra (IR; KBr disc, cm⁻¹)

-   -   3062, 1743, 1606, 1489, 1477, 1448, 1408, 1373, 1327, 1253,        1215, 1186, 1164, 1103, 1072, 1016, 1006, 995, 902, 858, 838,        781, 746, 700, 684, 640, 622, 574, 551, 536, 518, 501

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   POSITIVE M⁺263 (corresponding to (C₆H₅)₃S⁺)    -   NEGATIVE M⁻409 (corresponding to CF₃CH(OCOC₆H₄C₆H₅)CF₂SO₃ ⁻)

Synthesis Examples 13-26

Target compounds were synthesized as in Synthesis Example 11 except thatthe onium salts prepared in Synthesis Examples 2 to 8 and the sulfonatesalts prepared in Synthesis Examples 9 and 10 were used. The resultingonium salts PAG3 to PAG16 are shown below.

They were analyzed by spectroscopy. The NMR spectra (¹H-NMR and¹⁹F-NMR/DMSO-d₆) of PAG3 are shown in FIGS. 7 and 8. The NMR spectra(¹H-NMR and ¹⁹F-NMR/DMSO-d₆) of PAG4 are shown in FIGS. 9 and 10.

Synthesis Example 27 Synthesis of sodium1,1,3,3,3-pentafluoro-2-(pivaloyloxy)-propanesulfonate (Anion 3)

The target sodium sulfonate was obtained by following the procedure ofSynthesis Example 9 aside from using1,1,3,3,3-pentafluoropropen-2-yl-pivaloate which had been synthesized bya conventional technique.

The target compound was analyzed by spectroscopy. The data of IRspectroscopy are shown below. The NMR spectra (¹H-NMR and ¹⁹F-NMR/D₂O)are shown in FIGS. 11 and 12.

Infrared absorption spectra (IR; KBr disc, cm⁻¹)

-   -   1749, 1367, 1338, 1297, 1268, 1241, 1203, 1168, 1135, 1085, 998,        921, 838, 647, 628, 572

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   NEGATIVE M⁻313 (corresponding to CF₃CH(OCOC₄H₉)CF₂SO₃ ⁻)

Synthesis Example 28 Synthesis of sodium1,1,3,3,3-pentafluoro-2-(cyclohexane-carbonyloxy)propanesulfonate (Anion4)

The target sodium sulfonate was obtained by following the procedure ofSynthesis Example 9 aside from using1,1,3,3,3-pentafluoropropen-2-yl-cyclohexanecarboxylate which had beensynthesized by a conventional technique.

The target compound was analyzed by spectroscopy. The data of IRspectroscopy are shown below. The NMR spectra (¹H-NMR and ¹⁹F-NMR/D₂O)are shown in FIGS. 13 and 14.

Infrared absorption spectra (IR; KBr disc, cm⁻¹)

-   -   1749, 1375, 1342, 1286, 1270, 1245, 1222, 1199, 1172, 1159,        1133, 1083, 1070, 1008, 1000, 943, 833, 647

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   NEGATIVE M⁻339 (corresponding to CF₃CH(OCOC₆H₁₁)CF₂SO₃ ⁻)

Synthesis Example 29 Synthesis of sodium1,1,3,3,3-pentafluoro-2-(2-furoyloxy)-propanesulfonate (Anion 5)

The target sodium sulfonate was obtained by following the procedure ofSynthesis Example 9 aside from using1,1,3,3,3-pentafluoropropen-2-yl-furanyl-2-carboxylate which had beensynthesized by a conventional technique.

The target compound was analyzed by spectroscopy. The data of IRspectroscopy are shown below. The NMR spectra (¹H-NMR and ¹⁹F-NMR/D₂O)are shown in FIGS. 15 and 16.

Infrared absorption spectra (IR; KBr disc, cm⁻¹)

-   -   1743, 1720, 1575, 1471, 1400, 1367, 1346, 1321, 1305, 1272,        1243, 1197, 1168, 1130, 1083, 1016, 1006, 933, 892, 779, 750,        651

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   NEGATIVE M⁻323 (corresponding to CF₃CH(OCOC₄H₃O)CF₂SO₃—)

Synthesis Example 30 Synthesis of sodium1,1,3,3,3-pentafluoro-2-(2-naphthoyloxy)propanesulfonate (Anion 6)

The target sodium sulfonate was obtained by following the procedure ofSynthesis Example 9 aside from using1,1,3,3,3-pentafluoropropen-2-yl-naphthalene-2-carboxylate which hadbeen synthesized by a conventional technique.

The target compound was analyzed by spectroscopy. The data of IRspectroscopy are shown below. The NMR spectra (¹H-NMR and¹⁹F-NMR/DMSO-d₆) are shown in FIGS. 17 and 18.

Infrared absorption spectra (IR; KBr disc, cm⁻¹)

-   -   1745, 1365, 1344, 1288, 1261, 1238, 1195, 1164, 1130, 1105, 773,        759, 649

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   NEGATIVE M⁻389 (corresponding to CF₃CH(OCOC₁₀H₁₅)CF₂SO₃ ⁻)

Synthesis Example 31 Synthesis of sodium1,1,3,3,3-pentafluoro-2-(4-tert-butylbenzoyloxy)propanesulfonate (Anion7)

The target sodium sulfonate was obtained by following the procedure ofSynthesis Example 9 aside from using1,1,3,3,3-pentafluoropropen-2-yl-(4-tert-butyl)benzoate which had beensynthesized by a conventional technique.

The target compound was analyzed by spectroscopy. The NMR spectra(¹H-NMR and ¹⁹F-NMR/D₂O) are shown in FIGS. 19 and 20.

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   NEGATIVE M⁻389 (corresponding to CF₃CH(OCOC₆H₄C₄H₉)CF₂SO₃ ⁻)

Synthesis Example 32 Synthesis of sodium1,1,3,3,3-pentafluoro-2-(1-adamantane-carbonyloxy)propanesulfonate

The target sodium sulfonate was obtained by following the procedure ofSynthesis Example 9 aside from using1,1,3,3,3-pentafluoropropen-2-yl-adamantane-1-carboxylate which had beensynthesized by a conventional technique.

Synthesis Examples 33-43

Target compounds were synthesized as in Synthesis Example 11 except thatthe onium salts prepared in Synthesis Examples 1 to 8 and the sulfonatesalts prepared in Synthesis Examples 27 to 32 were used. The resultingonium salts PAG17 to PAG27 are shown below.

They were analyzed by spectroscopy. The NMR spectra (¹H-NMR and¹⁹F-NMR/CDCl₃, ¹H-NMR and ¹⁹F-NMR/DMSO-d₆) of PAG17, PAG18, PAG20,PAG22, PAG25, PAG26 and PAG27 are shown in FIGS. 21 to 34.

Synthesis Example 44 Synthesis of triphenylsulfonium1,1,3,3,3-pentafluoro-2-acetyloxypropane-1-sulfonate (PAG28) Hydrolysisof Carboxylic Ester in Anion Followed by Re-Esterification withCarboxylic Anhydride

In 104 g of methanol was dissolved 34.4 g of triphenylsulfonium1,1,3,3,3-pentafluoro-2-benzoyloxypropane-1-sulfonate prepared inSynthesis Example 11. 2.5 g of sodium hydroxide in 7.5 g of water wasadded to the solution whereupon reaction took place for one hour underice cooling. The reaction was monitored by thin layer chromatography(TLC), and the disappearance of the reactant spot was confirmed, afterwhich 6.8 g of 12N hydrochloric acid was added to quench the reaction.270 g of dichloromethane was added to the reaction solution, from whichthe organic layer was separated and concentrated, leaving 28 g of theconcentrate. To an aliquot (3.0 g) of the concentrate were added 28 g ofmethylene chloride and 0.7 g of pyridine. Under ice cooling, 0.8 g ofacetic anhydride was added dropwise to the solution, then 0.7 g oftriethylamine and 0.04 g of 4-(N,N-dimethylamino)pyridine added. Themixture was stirred for 4 hours. The reaction was quenched with 20 g ofwater, after which the organic layer was separated, washed with 50 g ofwater three times, and concentrated. The target compound was obtained as3 g of oil.

The target compound was analyzed by spectroscopy. The data of IRspectroscopy are shown below. The NMR spectra (¹H-NMR and¹⁹F-NMR/DMSO-d₆) are shown in FIGS. 35 and 36.

Infrared absorption spectra (IR; KBr, cm⁻¹)

-   -   3089, 3064, 2971, 1779, 1581, 1477, 1448, 1373, 1322, 1253,        1213, 1186, 1164, 1116, 1091, 1072, 995, 919, 750, 684, 642

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   POSITIVE M⁺263 (corresponding to (C₆H₅)₃S⁺)    -   NEGATIVE M⁻269 (corresponding to CF₃CH(OCOCH₃)CF₂SO₃ ⁻)

Synthesis Example 45 Synthesis of (4-hydroxyphenyl)diphenylsulfonium1,1,3,3,3-pentafluoro-2-benzoyloxypropane-1-sulfonate (PAG29)

In 60 g of dichloromethane was dissolved 6.7 g of4-tert-butoxyphenyldiphenylsulfonium1,1,3,3,3-pentafluoro-2-benzoyloxypropane-1-sulfonate (PAG4) prepared inSynthesis Example 14. Methanesulfonic acid, 0.1 g, was added to thesolution, which was heated and stirred at 40° C. for 3 hours. Theorganic layer was washed with 30 g of water three times, andconcentrated. Diethyl ether was added to the concentrate forcrystallization. The crystals were filtered and dried, obtaining thetarget compound in an amount of 4.9 g.

Analysis of the target compound by NMR spectroscopy (¹H-NMR/CDCl₃)confirmed the disappearance of the peak corresponding totert-butoxy(CH₃)C— in the reactant, with the target compound beingidentified. It was also analyzed by time-of-flight mass spectrometry.

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   POSITIVE M⁺279 (corresponding to (C₆H₅) 2 (c₆H₅O) S⁺)    -   NEGATIVE M⁻333 (corresponding to CF₃CH(OCOC₆H₅)CF₂SO₃ ⁻)

Synthesis Example 46 Synthesis of(4-methacryloyloxyphenyl)diphenylsulfonium1,1,3,3,3-pentafluoro-2-benzoyloxypropane-1-sulfonate (PAG30)

In 15 g of dichloromethane was dissolved 3 g of(4-hydroxyphenyl)diphenylsulfonium1,1,3,3,3-pentafluoro-2-benzoyloxypropane-1-sulfonate (PAG29) preparedin Synthesis Example 45. Methacryloyl chloride, 1 g, was added to thesolution, which was cooled in an ice bath, and 0.9 ml of triethylaminewas added dropwise. 30 g of 3N dilute hydrochloric acid was added, afterwhich the organic layer was separated, washed with 30 g of water threetimes, and concentrated. The concentrate was purified by silica gelcolumn chromatography (elute: dichloromethane/methanol 20/1 in weightratio), after which diethyl ether was added to the concentrate forcrystallization. The crystals were filtered and dried, obtaining thetarget compound in an amount of 3.5 g.

On analysis of the target compound by NMR spectroscopy (¹H-NMR/DMSO-d₆),spectral peaks were observed near 6.33 ppm, 5.97 ppm and 2.00 ppm,confirming the substitution of methacryloyl group. It was also analyzedby time-of-flight mass spectrometry.

Time-of-flight mass spectrometry (TOFMS; MALDI)

-   -   POSITIVE M⁺279 (corresponding to (C₆H₅) 2 (C₁₀H₉O₂) S⁺)    -   NEGATIVE M⁻333 (corresponding to CF₃CH(OCOC₆H₅)CF₂SO₃—)

Examples 1-16 & Comparative Examples 1-3 Evaluation of Resist Resolution

Resist compositions were prepared by dissolving the photoacid generatorsof Synthesis Examples, Polymers 1 to 8 as the base resin, dissolutionaccelerator DRR1, dissolution inhibitor DRI1, and basic compound in asolvent containing 0.01 wt % of surfactant FC-430 (Sumitomo 3M Co.,Ltd.) according to the formulation shown in Tables 1 and 2. Note thatPolymers 1 to 8, DRR1 and DRI1 are shown below. They were filteredthrough a Teflon® filter having a pore size of 0.2 μm, giving resistsolutions.

An antireflective coating liquid ARC-29A (Nissan Chemical Co., Ltd.) wascoated onto a silicon substrate and baked at 200° C. for 60 seconds toform an antireflective coating of 78 nm thick. The resist solution wasspin coated onto the antireflective coating and baked on a hot plate at120° C. for 60 seconds, forming a resist film of 200 nm thick. Theresist film was exposed by means of an ArF excimer laser microsteppermodel S305B (Nikon Corp., NA 0.68, σ 0.85, ⅔ annular illumination, Crmask), post-exposure baked (PEB) at 110° C. for 90 seconds, anddeveloped with a 2.38 wt % aqueous solution of tetramethylammoniumhydroxide (TMAH) for 60 seconds.

An optimal exposure dose (sensitivity Eop, mJ/cm²) was the exposurewhich provided a 1:1 resolution at the top and bottom of a 0.12-μm groupline-and-space pattern. The minimum line width (μm) of a line-and-spacepattern which was ascertained separate at this dose was the resolutionof a test resist. The formulation and test results of the resistcompositions are shown in Tables 1 and 2.

The solvents and basic compounds in Tables 1 and 2 are shown below aswell as the photoacid generators in Comparative Examples.

Solvent A: propylene glycol methyl ether acetate

Solvent B: cyclohexanone

Basic Compound A: tri-n-octylamine

Basic Compound B: triethanolamine

Basic Compound C: trismethoxymethoxyethylamine

Basic Compound D: tris(2-acetoxyethyl)amine

TPS-NfO: triphenylsulfonium perfluoro-1-butanesulfonate

TPS-PFOS: triphenylsulfonium perfluoro-1-octanesulfonate

TABLE 1 Formulation Example (pbw) 1 2 3 4 5 6 7 8 9 10 Polymer 1 80 80Polymer 2 80 80 Polymer 3 80 Polymer 4 80 Polymer 5 80 Polymer 6 80Polymer 7 80 Polymer 8 80 PAG1 4 4 4 4 4 4 4 4 PAG2 5 PAG3 5 PAG4 PAG7PAG10 PAG13 TPS-NfO TPS-PFOS Basic Compound A 0.5 0.5 0.5 0.5 BasicCompound B 0.5 0.5 0.5 Basic Compound C 0.5 0.5 0.5 Basic Compound DDRR1 DRI1 Solvent A 800 800 800 800 800 800 800 800 800 Solvent B 800Tests Sensitivity (mJ/cm²) 25 23 21 23 20 21 21 20 30 35 Resolution (μm)0.11 0.11 0.11 0.11 0.12 0.11 0.11 0.12 0.11 0.11

TABLE 2 Comparative Formulation Example Example (pbw) 11 12 13 14 15 161 2 3 Polymer 1 40 80 Polymer 2 40 40 60 80 80 40 Polymer 3 40 40Polymer 4 40 80 Polymer 5 40 20 Polymer 6 Polymer 7 Polymer 8 PAG1 4PAG2 PAG3 4 PAG4 5 PAG7 6 PAG10 6 PAG13 6 TPS-NfO 1 4 2 TPS-PFOS 1 4 3Basic Compound A 0.5 0.5 0.5 Basic Compound B Basic Compound C 0.5 0.50.5 Basic Compound D 0.5 0.5 0.5 DRR1 10 DRI1 10 Solvent A 600 800 800800 800 800 800 800 800 Solvent B 200 Tests Sensitivity (mJ/cm²) 38 3635 40 25 35 26 30 28 Resolution (μm) 0.11 0.11 0.1 0.11 0.11 0.11 0.110.11 0.11

Examples 17-27 Evaluation of Resist Resolution

Using the photoacid generators in Synthesis Examples, resistcompositions having the formulation shown in Table 3 were prepared as inExamples 1-16. They were similarly evaluated for resolution. Theformulation and test results of the resist compositions are shown inTable 3.

TABLE 3 Formulation Example (pbw) 17 18 19 20 21 22 23 24 25 26 27Polymer 1 80 80 40 Polymer 2 80 80 40 Polymer 3 80 80 Polymer 4 80 80Polymer 5 40 40 Polymer 8 80 PAG1 2 PAG17 6 5 4 PAG18 6 PAG20 6 6 6 6PAG22 5 PAG25 5 PAG26 6 TPS-NfO TPS-PFOS Basic Compound A 0.5 0.5 0.50.5 Basic Compound B 0.5 0.5 0.5 Basic Compound C 0.5 0.5 0.5 0.5 BasicCompound D Solvent A 800 720 800 800 560 800 800 800 720 800 560 SolventB 80 240 80 240 Tests Sensitivity (mJ/cm²) 24 27 23 21 21 20 22 24 26 2835 Resolution (μm) 0.11 0.11 0.11 0.11 0.12 0.11 0.11 0.12 0.11 0.110.12

Next, simulative immersion photolithography was carried out using theresist compositions of Examples 1, 4, 17, 19 and Comparative Example 1.Specifically, a resist film of 1250 nm thick was formed on a wafer by aprocedure as described above and exposed by means of an ArF excimerlaser microstepper model S307E (Nikon Corp., NA 0.85, dipole, 6% HTPSM).Immediately after the exposure, deionized water was fed over the entiresurface of the wafer, whereby the exposed surface of resist was immersedin deionized water for 60 seconds (puddle). The wafer was rotated tospin off the water, followed by ordinary PEB and development. The numberof defects in the pattern formed after development was counted by awafer inspection system WINWIN 50-1200L (Tokyo Seimitsu Co., Ltd.). Adefect density was computed therefrom.

Defect density(/cm²)=(total number of detected defects)/(test area).

-   -   Pattern formed: repetitive pattern of 80 nm/pitch 160 nm        line-and-space    -   Defect detection: light source UV, detection pixel size 0.125        μm, cell-to-cell mode

Additionally, the pattern profile in resist cross-section was observedunder a scanning electron microscope. The results are shown in Table 4.

TABLE 4 Defect density Pattern profile (/cm²) Example 1 rectangular<0.05 Example 4 rectangular <0.05 Example 17 rectangular 0.35 Example 19rectangular <0.05 Comparative Example 1 extreme T-top 10

As is evident from Tables 1 to 4, the resist compositions of theinvention have a high sensitivity and high resolution and invite neitherprofile changes nor defects during a long term of water rinsing ascompared with the prior art composition, suggesting an ability to complywith the immersion photolithography. As demonstrated in SynthesisExample 42, the photoacid generator capable of generating a sulfonicacid having formula (1a) can be converted into lower molecular weightcompounds as a result of its ester moiety being decomposed byhydrolysis, especially alkaline hydrolysis. The load to the environmentis thus reduced as compared with prior art photoacid generators capableof generating perfluoroalkylsulfonic acids or partially fluorinatedalkylsulfonic acids.

Japanese Patent Application Nos. 2005-109903 and 2005-316096 areincorporated herein by reference.

Although some preferred embodiments have been described, manymodifications and variations may be made thereto in light of the aboveteachings. It is therefore to be understood that the invention may bepracticed otherwise than as specifically described without departingfrom the scope of the appended claims.

1. A photoacid generator for chemically amplified resist compositionswhich generates a sulfonic acid upon exposure to high-energy radiationselected from UV, deep-UV, electron beam, x-ray, excimer laser,gamma-ray and synchrotron radiation, said sulfonic acid having thegeneral formula (1a):CF₃—CH(OCOR)—CF₂SO₃ ⁻H⁺  (1a) wherein R is a substituted orunsubstituted, straight, branched or cyclic C₁-C₂₀ alkyl group or asubstituted or unsubstituted C₆-C₁₄ aryl group.
 2. A N-sulfonyloxyimidecompound having the general formula (3a):

wherein R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup, X and Y are each independently hydrogen or a substituted orunsubstituted C₁-C₆ alkyl group, or X and Y may bond together to form asaturated or unsaturated C₆-C₁₂ ring with the carbon atoms to which theyare attached, and Z is a single bond, double bond, methylene group oroxygen atom.
 3. An oxime sulfonate compound having the general formula(3b):

wherein R is a substituted or unsubstituted, straight, branched orcyclic C₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₄ arylgroup, n is 0 or 1, when n is 0, p is a substituted or unsubstitutedC₁-C₂₀ alkyl group or a substituted or unsubstituted C₆-C₁₂ aryl group,when n is 1, p is a substituted or unsubstituted C₁-C₂₀ alkylene groupor a substituted or unsubstituted C₆-C₁₂ arylene group, EWG is a cyano,trifluoromethyl, perfluoroethyl, perfluoropropyl, 5H-perfluoropentyl,6H-perfluorohexyl, nitro or methyl group, and when n is 1, two EWG's maybond together to form a ring of 6 carbon atoms with the carbon atoms towhich they are attached.
 4. A resist composition comprising a baseresin, an acid generator, and a solvent, said acid generator comprisinga photoacid generator which generates a sulfonic acid having formula(1a) as set forth in claim
 1. 5. The resist composition of claim 4,wherein said base resin is at least one polymer selected from the groupconsisting of poly(meth)acrylic acid and derivatives thereof,alternating copolymers of a cycloolefin derivative and maleic anhydride,copolymers of ternary or more components comprising a cycloolefinderivative, maleic anhydride, and polyacrylic acid or derivativesthereof, cycloolefin derivative-α-trifluoromethyl acrylate copolymers,polynorbornene, ring-opening metathesis polymers, and hydrogenatedring-opening metathesis polymers.
 6. The resist composition of claim 4,wherein said base resin is a polymeric structure containing siliconatoms.
 7. The resist composition of claim 4, wherein said base resin isa polymeric structure containing fluorine atoms.
 8. A chemicallyamplified positive resist composition comprising a base resin as setforth in claim 5, a photoacid generator which generates a sulfonic acidhaving formula (1a) as set forth in claim 1, and a solvent, wherein saidbase resin is insoluble or substantially insoluble in a liquiddeveloper, and becomes soluble under the action of the acid.
 9. Thechemically amplified positive resist composition of claim 8, furthercomprising a basic compound.
 10. The chemically amplified positiveresist composition of claim 8, further comprising a dissolutioninhibitor.
 11. A process for forming a pattern comprising the steps ofapplying the resist composition of claim 4 onto a substrate to form acoating, heat treating the coating and exposing it to high-energyradiation having a wavelength of up to 200 nm through a photomask, andoptionally heat treating and developing the exposed coating with adeveloper.
 12. The process of claim 11, wherein the exposing step relieson immersion lithography comprising directing radiation from an ArFexcimer laser having a wavelength of nm through a projection lens, witha liquid such as water, glycerin or ethylene glycol intervening betweenthe coated substrate and the projection lens.